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Full text of "shipboard electrical systems"

SHIPBOARD 
ELE CTR I C AL SYSTEMS 



NAVAL EDUCATION AND TRAINING COMMAND 
NAVEDTRA 10864-D 



/v; 



PREFACE 



This text is written primarily for junior officers of the U. S* Navy 
and Naval Reserve as an aid in gaining more knowledge of the electrical 
equipment and electrical systems installed aboard Navy ships. Repre- 
sentative equipments and systems are described by the use of pictoral 
views and block diagrams with electrical schematics being kept to a 
minimum. The operating principles of any of the electrical or electronic 
devices or circuits mentioned in the text may be found in Basic Electricity 
and NAVPERS 10086-B or Basic Electronics. NAVPERS 10087-C. 
Information relating to shipboard machinery other than electrical and 
the organization and administration of the engineering department 
is contained in Principles of Naval Engineering, NAVPERS 10788-B 
and Engineering Administration, NAVPERS 10858~E 

This text provides hints on managing the maintenance of generating 
equipment, distribution systems, motors, controllers lighting systems, 
degaussing systems, auxiliary equipment, alarm and warning systems, 
ships indicating and dead reckoning equipment, telephone systems, 
amplified voice systems and gyrocompasses. Safety precautions required 
in maintenance and operation of the above equipment and systems are 
stressed. 

This text was prepared by the Naval Education and Training Program 
Development Center, Pensacola, Florida for the Chief of Naval Education 
and Training (CNET) personnel. Technical assistance was provided by 
the Electrical Schools located at Great Lakes, IL, Norfolk, VA, and 
San Diego, CA. 



Stock Ordering No. 
0502-LP-054-3250 



Revised 1976 



Published by 
NAVAL EDUCATION AND TRAINING SUPPORT COMMAND 



UNITED STATES 

GOVERNMENT PRINTING OFFICE 
WASHINGTON, D.C.: 1976 



THE UNITED STATES NAVY 

GUARDIAN OF OUR COUNTRY 

The United States Navy is responsible for maintaining control of the sea 
and is a ready force on watch at home and overseas, capable of strong 
action to preserve the peace or of instant offensive action to win in war. 

It is upon the maintenance of this control that our country's glorious 
future depends; the United States Navy exists to make it so. 



WE SERVE WITH HONOR 

Tradition, valor, and victory are the Navy's heritage from the past. To 
these may be added dedication, discipline, and vigilance as the watchwords 
of the present and the future. 

At home or on distant stations we serve with pride, confident in the respect 
of our country, our shipmates, and our families. 

Our responsibilities sober us; our adversities strengthen us. 

Service to God and Country is our special privilege. We serve with honor. 

THE FUTURE OF THE NAVY 

The Navy will always employ new weapons, new techniques, and 
greater power to protect and defend the United States on the sea, under 
the sea, and in the air. 

Now and in the future, control of the sea gives the United States her 
greatest advantage for the maintenance of peace and for victory in war. 

Mobility, surprise, dispersal, and offensive power are the keynotes of 
the new Navy. The roots of the Navy lie in a strong belief in the 
future, in continued dedication to our tasks, and in reflection on our 
heritage from the past. 

Never have our opportunities and our responsibilities been greater. 



ii 



CONTENTS 



CHAPTER page 

1. Safety i 

2. Power Supplies . 1;L 

3. Distribution Systems 3i 

4. Motors and Controllers . 53 

5. Shipboard Lighting . . . 59 

6. Degaussing o 93 

7 Auxiliary Shipboard Equipment 118 

80 Alarm and Warning Systems 137 

9. Ship's Indicating, Order, and Metering Systems 159 

10. Interior Communications Telephone Systems . . 193 

llo Amplified Voice Systems o 227 

12. Gyrocompasses . a 255 

INDEX ..o.o 282 



iii 



CREDITS 



The illustrations indicated below are included in this edition of 
Shipboard Electrical Systems through the courtesy of the designated 
55i^n7~liid publisher. Permission to use the illustrations are grate- 
fully acknowledged. 

Source Figure 

General Electric Company 2-4, 2-5 

VVestingbouse Electric Corporation 2-6, 2-7, 2-8, 2-9, 3-1, 3-2, 

3-12 

Woodward Governor Company 2-17 

VA RO , Inc , Biom etric s Instrum ent 

Corporation 2-20 

Teledyne Inet 187.5 KVA, 150 KW, 

60 Ha to 400 Hz Power Converter 2-22 

ITE Circuit Breaker Company 3-10, 3-14, 3-16 

Left Illustration ONLY, ITE Circuit 

Breaker Company 3-11 

Cutler Hammer Incorporated 4-12, 4-14 

The Louis A His Company, Drives 

and Systems Division 6-15 

Gaibraith- Pilot Marine Division of 
Marine Electric Railway Products 

Division, Inc. 9-4 

U. S. Instrument Corporation 10-5, 10-6 

Strom berg-Carlson Corporation 10-27, 10-28 

RCA 11-16, 11-17 

Sperry Marine Systems 12-19, 12-20, 12-23, 12-24 



IV 



CHAPTER 1 

SAFETY 



In accordance with article 0712 of U.S. Navy 
Regulations the commanding officer is vested 
with the responsibility of safety aboard his ship. 
In this regard, he is to ensure that all personnel 
under his command are instructed in, and comply 
with, applicable safety precautions and proce- 
dures. While the commanding officer cannot 
delegate his responsibility, he must necessarily 
delegate authority to his officers and petty officers 
to ensure that all safety precautions are under- 
stood and, more importantly, enforced. As 
Division Officers you will be required to thor- 
oughly understand all safety notices and in- 
structions and have your division or department 
comply with them. 

Some of your sources of safety information are: 
Navy Safety Precautions for Forces Afloat, 
OPNAV INSTRUCTION 5100.19 jNAVSHIPS' Tech- 
nical Manual, Chapter 300; Electronics Instal- 
lation & Maintenance Book (EIMB) General, 
NAVSHIPS' 0967-LP-000-0100;HowtoKeep Elec- 
tricity from Killing You, NAVSHIPS' 0981-LP- 
052-8500; Electric Shock Its Cause & Prevention, 
NAVSHIPS' 0900-LP-007-9010; Electric Shock 
and Its Prevention, NAVSHIPS' 0283-LP-236- 
0000; Safety Notes from NAVSEA Journal & 
Ships Safety Bulletin; EM 3 & 2, NAVEDTRA 10546, 
and Fathom Magazine published by Naval Safety 
Center, Norfolk, You should be familiar with all 
of these publications and ensure that your division 
or department complies with their contents. 

All safety information in this chapter is ex- 
tracted from the above listed publications. The 
information contained herein should be used for 
general guidance and not as final authority* 



ELECTRICAL HAZARDS 

Probably more deaths aboard ship occur from 
electric shock than from any other type of accident. 
Prevention of electric shock aboard ship neces- 
sitates strict compliance with all safety require- 
ments pertinent to the various work areas as well 



as strict adherence to all prescribed safety pre- 
cautions for the type of job concerned, 

ELECTRIC SHOCK 

Flow of current through the body is the cause 
of electric shock. Factors determining the extent 
of the body damage which results from electric 
shock are (1) the amount and duration of the 
current flow, (2) the parts of the body involved, 
and (3) the frequency of the current, if a.c. 
In general, the greater the current or the longer 
the current flows, the greater will be the body 
damage,. Body damage is also greatest when the 
current flow is through or near nerve centers 
and vital organs. For example: If a 60-hertz 
alternating current is passed through a man 
from hand to hand, or from hand to foot, and is 
gradually increased from zero, the following 
effects will occur: 

1. At approximately 1 milliampere (0.001 
ampere) the shock will be perceptible 

2. At approximately 10 milliamperes (0.01 
ampere) the shock will be sufficiently intense to 
prevent voluntary control of the muscles and the 
man may be unable to let go or free himself 

3. At approximately 100 milliamperes (0.1 
ampere) the shock will be fatal if it lasts for 
1 second. 

High frequency currents have a tendency 
to flow along the surface of the skin (skin 
effect); persons coming into contact with these 
currents usually suffer severe burns although 
the current may not penetrate the body. 

Two conditions must be present for an electric 
current to flow through the body and cause elec- 
tric shock. 

1. The body or some part of the body must 
form part of a closed circuit; and 



SHIPBOARD ELECTRICAL SYSTEMS 



2* Somewhere in the closed circuit there 
must be a voltage, or a difference in potential, 
to cause a current flow. 

It follows, then, that to prevent electric shock, 
you should always ensure that your body never 
forms a part of a closed circuit. 

Tests made by the National Bureau of Standards 
show that the resistance of the human body may 
be as low as 300 ohm s under unfavorable conditions 
such as those caused by salt water and perspi- 
ration. These test results indicate immediately 
that it is possible for a potential difference 
as low as 30 volts to cause the fatal 0.1 ampere 
current flow through the body. It is true that the 
conditions of the above tests were extremely 
unfavorable,. However, the results leave no doubt 
as to the dangers relative to the 120- volt circuits 
aboard ship and as to the necessary precautions 
that all personnel must observe continually. 

Causes of Electric Shock 

Practically all electric shocks are caused by 
human failure rather than by equipment failure. 
Equipment may suddenly fail and cause fatal 
shock even if it were skillfully designed for 
safety, thoroughly tested before use, and used 
in accordance with applicable safety precautions. 
This can happen, but rarely does. Nearly all 
shipboard deaths due to electric shock have been 
caused by human failure manifested in one or 
more of the following ways: 

1. Unauthorized use of, or unauthorized modi- 
fications to, equipment. 

2 Failure to observe the applicable safety 
precautions whenusing equipment or when working 
on or near energized equipment* 

3. Failure to repair equipment which is known 
to be defective and has previously given a mild 
shock to user So 

4. Failure to test and inspect equipment for 
defects, or failure to remedy all defects found 
by tests and inspections. 

All of these failures may be summarized as 
failure to observe applicable safety precautions. 



SAFETY TRAINING 
PROGRAM 

The fields of electricity and electronics de- 
mand an effective safety training program because 
of the inherent hazards. Technicians working 



with the electrical systems are generally aware 
of the safety precautions but, due to familiarity, 
sometimes "overlook" them. In this respect 
a vigorous training program is not just a good 
idea; it is a MUST. 

There are many systems and plans to guide 
you in implementing a safety training program. 
You will find some excellent ideas in Standard 
Organization and Regulations of the U.S. Navy, 
OPNAVINST 3120 32 and in the Division Officers 
Guide. 

The training plan you select is not as important 
as that you have a system and make it work to have 
a safety-conscious division. 



SAFETY REQUIREMENTS 

As a division officer of the electrical depart- 
ment aboard ship, you will be dealing with some 
special tasks which are unique to the electrical 
field. A basic understanding of these situations 
will prove helpful to you in maintaining safety 
precautions within the division,, 

IN WORK AREAS 

Safety requirements concerning the various 
shops and other work areas aboard ship are 
prescribed by the NAVSHIPS' Technical Manual 
and other authority. The requirements for elec- 
trical work areas include the following: 

1. Rubber matting that meets military speci- 
fications is to be provided in the front and rear 
of all electrical switchboards including 1C and 
weapons control switchboards. This rubber mat- 
ting is also required in front of all announcing 
system amplifiers and control racks, on areas 
around electronic equipment, and in front of 
test benches or tables in electrical and elec- 
tronic shops. The matting should be cemented to 
the deck except on grating and removable deck 
plates. 

2. HIGH VOLTAGE signs (fig. 1-1) and suit- 
able guards are to be provided wherever the 
voltage exceeds 30 volts in exposed live circuits 
or equipment 

3. All rear service switchboards are required 
to have an expanded metal enclosure with a door. 
The enclosure is NOT to be used as a storage 
space. A safety poster, such as shown in figure 
1-2, posted on the door might be agood reminder. 



Chapter 1 SAFETY 




HIGH 
VOLTAGE 



40.67(31) 
Figure 1-1, High voltage warning sign. 



4. First aid treatment (fig. 1-3) for electrical 
lock and other applicable electrical safety 
ecautions must be posted in all areas containing 
ajor units of electrical or electronic equipments. 

5. NO SMOKING signs are to be posted in 
>aces where storage batteries are charged 
id in all other spaces where explosive vapors 
ay be present, 

6. Workbenches must be insulated (fig. 1-4) 
j prescribed by General Specifications for 
lips of the U.S. Navy, NAVSHIPS' 0902-001-500. 

warningplate which reads, ELECTRIC SHOCK 
A.NGER DO NOT TOUCH ENERGIZED CIR- 
LJITS must be installed over the workbench, 
rtificial respiration instructions and a 
ascription of an approved method (fig. 1-5) 
reselling personnel in contact with energized 
rcuits must also be posted. 

i PORTABLE 
LECTRICAL EQUIPMENT 

Navy specifications for metal-cased portable 
ols require that the electric cord for the tools 
\ provided with a distinctively marked grounding 
>nductor in addition to the conductors that 
L PPty power to the tool. Past practice was to 
\Q red for the grounding conductor in three- 
inductor cables for portable tools and equipment 
id green in four-conductor cables, except for a 
w cases in which black was used in the cords 
r some items of portable equipment. Revised 
iecifications require that green be used for 
e grounding conductor in cables for all new 




40.67(67B) 



Figure 1-2. Safety poster. 



metal-cased portable tools and equipment. The 
end of the grounding conductor which is within 
the tool should be connected to the metal housing, 
the other end should be grounded; that is, con- 
nected to the ship's metal structure. To provide 
a convenient means of connecting the grounding 
conductor to ground, NAVSEA has standardized 
the use of grounded- type plugs and receptacles 
which automatically make this connection when the 
plug is inserted into the receptacle. 

Nonconducting case-type portable electric 
tools (plastic-cased, shockproof) do not require 
grounding cords or plugs. The two-conductor 
cords and two-prong ungrounded connector plugs 
furnished on these plastic-cased tools are accept- 
able and can be inserted into blade-type recep- 
tacles aboard ship which may be labeled 
* 'WARNING: Insert 3-prong grounded plugs only," 

Before using portable electrical equipment 
for the first time, check the plug connections of 
the equipment for correct wiring. The test of 



SHIPBOARD ELECTRICAL SYSTEMS 



ARTIFICIAL RESPIRATION 

MOUTH-TO-MOUTH OR MOUTH-TO-NOSE 

RESCUE BREATHING 

PLACE CASUALTY ON BACK IMMEDIATELY 

DON'T WASTE TIME MOVING TO A BETTER PLACE OR 
LOOSENING CLOTHING. 

QUICKLY CLEAR MOUTH AND THROAT 

REMOVE MUCUS, FOOD AND OTHER OBSTRUCTIONS. 

TILT HEAD BACK AS FAR AS POSSIBLE 

THE HEAD SHOULD BE IN A "CHIN-UP" OR "SNIFF" POSI- 
TION AND THE NECK STRETCHED. 



/LIFT LOWER JAW FORWARD 

GRASP JAW BY PLACING THUMB INTO CORNER OF MOUTH. 
DO NOT HOLD OR DEPRESS TONGUE. 

PINCH NOSE SHUT OR SEAL MOUTH 
PREVENT AIR LEAKAGE. 

OPEN YOUR MOUTH WIDE AND BLOW 

TAKE A DEEP BREATH AND BLOW FORCEFULLY (EXCEPT 
FOR BABIES) INTO MOUTH OR NOSE UNTIL YOU SEE CHEST 
RISE. 

LISTEN FOR EXHALATION 

QUICKLY REMOVE YOUR MOUTH WHEN CHEST RISES. LIFT 
JAW HIGHER IF VICTIM MAKES SNORING OR GURGLING 
SOUNDS. 

REPEAT STEPS SIX AND SEVEN 12 TO 20 TIMES 
PER MINUTE 

CONTINUE UNTIL VICTIM BEGINS TO BREATHE NORMALLY. 

* FOR INFANTS SEAL BOTH MOUTH AND NOSE WITH YOUR 
MOUTH 

BLOW WITH SMALL PUFFS OF AIR FROM YOUR CHEEKS. 



T) CLEAR THE MOUTH 
AND THROAT 



TILT HEAD BACK 
AND LIFT JAW 




PINCH NOSE 
(OR SEAL LIPS) 



B 




Figure 1-3* Artificial respiration and cardiac massage. 

4 



4.224 



Chapter 1 SAFETY 




WORKING AREA (TOP, TOP EDGE, FRONT OF DOORS AND DRAWERS) 
INSULATED WITH 3/8 INCH BENELEX 401 

ALLOTHER EXPOSED METAL SURFACES IN THE WORKING AREA 
(BENCH FRONT AND SIDES, KNEE HOLE SIDE, UNDERSI DE OF TOP) 
INSULATED WITH 1/8 INCH BENELEX 401. 

RUBBER MATTING, EITHER GREY OR GREEN BUTATLEAST 
3 FEET WIDE. 



77.308 
Figure 1-4 Typical electric workbench. 



portable equipment should be conducted in a 
workshop equipped with a nonconducting surface 
workbench and a diamond-tread, rubber deck 
covering. Electricians making the tests should 
wear rubber gloves during tests. 



CONNECTING AND 
DISCONNECTING 
SHORE POWER 

Because of the variety of shore power arrange- 
ments and hardward items used in both ship and 
shore installations, no specific installation in- 
structions can be outlined in detail in this manual* 
However, there are instructions and procedures 
that should be followed before and during con- 
nection to shore power. More detailed instruction 
is usually provided by type commanders or your 
own ships instruction. 

Because of the dangers to personnel and equip- 
ment, the connecting and disconnecting of shore 
power should be under the direct supervision 




FROM LIVE WIRE 



1. DO NOT TOUCH VICTIM OR WIRE 

2. DISCONNECT POWER IF POSSIBLE 

3. USE DRY WOOD POLE OR DRY 
ROPE TO REMOVE WIRE 

4. RESUSCITATE IF NECESSARY 




40,67(27D) 



Figure 1-5. -Safety poster. 



of the electrical officer s a qualified leading 
electrician* and the shore activity personnel*. 
All cables should be visually inspected for 
any signs of defect* such as, cracks, bulges, or 
indications of overheating. (Spliced cable is 
extremely dangerous unless splices are properly 
made.) Check the cables with a 500 V meggar 
for insulation resistance between phases and 
from each phase to ground. 

Rope off the work area surrounding the ship's 
shore power terminal box and tag with high- 
voltage signs. With the ship's shore power breaker 
tagged in the open position, test the terminals in 
the terminal box to ensure they are deenergized. 
With a 500 V meggar, test the insulation resistance 
between the terminals and from each terminal 
to ground. 

Lay out the cable between the ship's terminal 
box and the terminal box supplying power from 
the shore activity, remembering to allow slack for 
tides. Cables should not be permitted to rest on 
sharp or ragged objects,, Excess cable should be 
neatly faked out in a manner that will minimize 
damage from vehicle and pedestrian movement. 
Connect the cables to the ship's shore power 



SHIPBOARD ELECTraCAL SYSTEMS 



terminals according to the phase or polarity 
markings in the box and on the cables. 

With a voltmeter, check to ensure that the 
supplying activity's shore terminals are de- 
energized; then connect the cables to the shore 
terminals. 

Check for proper phase rotation by energizing 
the shore power breaker from the supplying 
activity. With proper phase rotation determined, 
proceed with the transfer of electrical load to 
shore power in accordance with Engineering 
Department Operating Instructions. 

After the cables are carrying the load, make 
an inspection of the cable and connections to 
detect any overheating. 

When disconnecting shore power, observe the 
same safety precautions outlined in the connecting 
sequence except for meggering cables and check- 
ing phase rotation. ENERGIZED SHORE POWER 
CABLES SHOULD NOT BE MOVED, 

IN USING CLEANING 
SOLVENTS 

Avoid using solvents for cleaning electrical 
equipment as much as possible because of their 
corrosive action, the possible injury to some 
insulating materials, the risk of fire, and espe- 
cially because of their toxicity. 

If it is necessary to use a solvent, the 
choice of solvent will depend on the instructions 
on the solvent label, the fire risk involved, and 
the facilities for maintaining adequate ventilation. 
It might be beneficial to try a small amount on the 
insulation to deter mine whether it will be injurious 
to the insulation. 

Inhibited methyl chloroform (1,1,1 trichloro- 
ethane) is the solvent approved for use on elec- 
trical equipment to remove grease and pasty 
substances consisting of- oil and carbon or dirt. 
This solvent is toxic and should be used with 
care since concentrations of the vapor are 
anesthetic and can be fatal. Dangerous concen- 
trations of the vapor may cause irritation of 
the eyes, dizziness, or disorientation. If any 
of these symptoms occur, you will know imme- 
diately that the amount of methyl chloroform 
being breathed is dangerously high. Personnel 
must secure the operation and evacuate the 
space until proper ventilation is obtained. To 
avoid misuse of this solvent, surface ships shall 
stock only 1-quart containers. 



Precautions with 
Cleaning Solvents 

During the use of any solvent the following 
rules MUST be observed: 

1. Guard carefully against fire. 

2. Use explosion-proof portable lights if sup- 
plementary lighting is required. 

3. Have fire extinguishers available for im- 
mediate use. 

4. Prevent possible sparks caused by one 
metallic object striking another. 

5. If a spray or atomizer is used, ground the 
nozzle. 

6. Avoid saturation of the operator's clothing 
with the solvent. Wear impervious (solvent re- 
sistant) gloves to avoid contact with the skin. 
Wear appropriate eye/face protective devices 
when splash hazards exist (e.g. when pouring 
solvent, etc.) 

7. Provide adequate ventilation by means of 
exhaust fans or other suitable means. 

8. When inhibited methyl chloroform or tri- 
chloroethane is being used, protection must 
be provided against breathing the fumes, and the 
operators should be under the observation of 
someone familiar with artificial respiration. 

9o Use of solvent in closed or very confined 
spaces, where ventilation is lacking and for 
some reason cannot be provided, requires that 
fullface air supply respirators and related con- 
trols be used. (Refer to damage control procedures 
involving use of "buddy" system, lifelines, etc.). 

10. Where normal (comfort) ventilation is 
present and very small volumes of cleaning 
solvent are used (few ounces, at most), the 
minimum requirement is proper use of approved 
organic vapor (charcoal) respirators. The pro- 
cedure MUST be studied to minimize exposure 
to the user, to adjacent spaces, and to nearby 
personnel. 

11. Where larger volumes of solvent are used 
indoors, specially applied exhaust ventilation 
and fullface air supply respirators, or equivalent 
respiratory protection, are recommended. 

12. When portable exhaust ventilation is ap- 
plied, the exhaust face (exhaust end of the 
flexible duct system) must be placed near the 
operation for best capture of the "fumes." The 
direction of ventilation should be checked to 



Chapter 1 SAFETY 



assure that fumes are being exhausted froin the 
space and that the exhausted air is discharged 
topside away from personnel and openings to 
prevent recirculation of the fumes into other 
occupied interior spaces. 

13. Do not apply solvent to hot equipment or 
use it in the presence of open flames. 

14. Assure that solvents are properly labeled 
according to hazards, that they are stored prop- 
erly, and that adequate marking/labeling is 
carried over into any subdivisions or transfer 
of material into other containers. 

IN MAINTENANCE AND 
REPAIR WORK 

When military considerations require that 
electrical repair or maintenance work be per- 
formed but prohibit deenergizing the circuits 
involved, extreme measures of precaution must 
be used. The work should be accomplished only 
by adequately supervised personnel who are 
fully cognizant of the dangers involved. Every 
care should be taken to insulate the person 
performing the work from ground and to use all 
practical safety measures. The following pre- 
cautions should be taken when applicable: 

1. Provide ample illumination. 

2. The person doing the work should not wear 
wrist watch, rings, watch chain, metal articles, 
or loose clothing which might make accidental 
contact with live parts or which might accidentally 
catch and throw some part of his body into contact 
with live parts. Clothing and shoes should be as 
dry as possible. 

3. Insulate the worker from ground by means 
of insulating material covering any adjacent 
grounded metal with which he might come in 
contact. Suitable insulating materials are dry 
wood, rubber mats, dry canvas, dry phenolic 
material, or even heavy dry paper in several 
thicknesses, Be sure that any such insulating 
material is dry, has no holes in it, and has no 
conducting materials embedded in it. Cover 
areas sufficiently to permit adequate latitude 
for movement by the worker in doing the work. 

4. Cover all metal, hand-held work tools with 
an electrical insulating material. Taping method: 
Cover the handle and as much of the shaft of the 
tool as practical. Use two layers of rubber or vinyl 
plastic tape, half lapped. Coating Method: Coat 
tools with plastisol. 

In an emergency, when time does not permit 
application of the above materials, cover the tool 
handles and tool shafts with cambric sleeving, 



synthetic resin flexible tubing, or insulation tubing 
removed from scraps of rubber electric cable. 

5. Insofar as practical, provide insulating 
barriers between the work to be done and any 
live metal parts immediately adjacent to the 
work. 

6. Use only one hand to accomplish the work, 
if practical. 

7. Use a rubber glove on the hand not used 
for handling tools. If the work being done permits, 
wear rubber gloves on both hands. 

8. Have men stationed by circuit breakers 
or switches and have the telephone manned if 
necessary, so that the circuit or switchboard 
can be deenergized immediately in case of 
emergency. 

9. A man qualified in mouth-to-mouth resusci- 
tation and cardiac massage for electric shock 
should be immediately available while the work 
is being done. 

10. Energized switchboards are a great source 
of danger. No work shall be undertaken on ener- 
gized switchboards unless approval of the Com- 
manding Officer has been obtained. 

11. Be sure that the connections of removable 
test leads on portable meters are tight. The 
free end of an energized test lead which comes 
adrift from its meter during a check of live 
circuits is both a shock and a fire hazard. 

WHILE WORKING ALOFT 

At times, personnel are required to go aloft 
for maintenance on running lights, to work on 
wind direction and intensity equipment, etc. 
Aside from the obvious hazard of falling from 
the mast, certain other hazards exist: asphyxiation 
from stack gases, electric shock, overexposure to 
radiation from radar equipment, contact with 
rotating or oscillating antennas, and overexposure 
to inclement weather conditions. 

Because of the numerous hazards, permission 
to go aloft must be obtained from the Officer 
of the Deck. Before granting permission, the OOD 
shall ensure that all power to appropriate radio 
and radar antennas is secured and that the con- 
trols associated with the antenna are tagged 
"Secured, Men Aloft." The OOD shall notify 
ships tied alongside of his intent to send men 
aloft and they will maintain the same safety 
precautions. The OOD shall also notify the 
Engineer Officer of the location of the men working 
aloft so he can take the necessary precautions 
to prevent such operations as lifting boiler 
safety valves or blowing tubes or whistles. 



SHIPBOARD ELECTRICAL SYSTEMS 



Before sending any men aloft, the Officer in 
Charge shall ensure that the men have read 
and that they fully understand all the regulations 
and safety precautions involved in going ploft. 

Some of these regulations are listed below: 

1. A man going aloft shall have the assistance 
of another man. 



2. Man working aloft shall wear a standard 
Navy approved safety harness and safety lines 
and shall use the saf-t-climb fall prevention 
system , 

3 e Do not attempt to climb while loaded 
with tools. Keep both hands free for climbing. 

4. Ensure yourself of good footing and grasp 
at all times. 

5 9 All tools and equipment shall be secured 
with preventer lines. 

6. Have assistants stand clear and keep all 
hands clear from below the working area. 

7. Men going aloft shall wear tight clothing. 
Loose or baggy clothing presents the hazard 
of becoming caught or entangled. 

8. When working on the stack, men shall be 
particularly cautious to avoid dangerous gases 
and fumes* 

9. The Officer of the Deck shall be notified 
immediately when work aloft has been completed. 



NONSTANDARD 
ALTERATIONS AND 
EQUIPMENT 

Many electrical hazards are introduced to the 
ship by nonstandard equipment (personal equip- 
ment) and nonstandard alterations (jury rigs). 
Shipboard 115- volt, 60-'Hz lighting and receptacle 
circuits are ungrounded,, In an ungrounded system 
both conductors of the 115-volt system are above 
ground potential and are a shock hazard. For this 
reason use of personal electrical equipment, 
which is normally designed to operate on 115-volt, 



60-Hz grounded systems (the normal residential 
power), is discouraged aboard ship. In much of 
this equipment the chassis forms a part of the 
circuit and the exposed metal parts are energized 
thereby creating the danger of shock to personnel 
who touch them. Moreover, grounding of these 
metal parts to the ship's structure would place 
a ground on the 115-volt system, jeopardizing 
continuity of power. Personal equipment may be 
permitted for use aboard ship if the following 
conditions are met. 

a. Adequate government-owned equipment is 
not available to meet the need, 

b. The equipment has been inspected by the 
electrical/electronic shop and approved as safe* 
Approved equipment shall be tagged and shall 
indicate the interval between inspections. The 
interval between inspections shall not exceed 6 
months. 

The approval criteria for personal equipment 
can be found in NAVSHIPS' Technical Manual, 
Chapter 300. 

Jury rigs, such as bypassing overloads, over- 
fusing circuits, rendering electrical interlocks 
inoperative and any other unauthorized design 
changes to equipment, are prohibited* 



SAFETY INSPECTIONS 

Conducting frequent informal safety inspec- 
tions is one of the most effective methods to ensure 
that precautions and accident prevention measures 
are being adhered to. These inspections should be 
used to identify and eliminate the various elec- 
trical safety hazards and should be made on a 
continuing basis. 

Some of the more common discrepancies you 
should look for on your tours are open covers 
on fuse and power panels, meters not calibrated, 
circuits over fused, improperly stowed equipment 
near switchboards, workbenches not properly 
insulated, and portable electric tools not safety 
inspected in accordance with PMS. 

Electrical safety posters of the type shown in 
figure 1-6 are useful as safety reminders and in 
promoting safety. Posters of this type should be 
changed and rotated regularly to different working 
areas so as to draw attention to them 



8 



Chapter 1 SAF ETY 



ALL SHOOK UP? 




I|GR< 

EJ 



GROUND IT BEFORE 



IT GROUNDS YOU! 





A GOOD THING 
TO KEEP IN MIND 




USING 
PORTABLE ELECTRIC 




Figure 1-6. Safety posters. 



40.67(77C) 



SHIPBOARD ELECTRICAL SYSTEMS 




Figure 1-6, Safety posters continued. 



4067(67B) 



10 



CHAPTER 2 



POWER SUPPLIES 



Ships of the U.S. Navy use electrical energy 
for a variety of applications which range froin 
simple lighting circuits to sophisticated and 
complex weapons circuits and electronic circuits. 
The electrical power is generated by power 
supplies. 

In this chapter we shall identify the different 
types of power supplies, their basic operations, 
their driving units and their regulation. We 
shall give a basic explanation of how an elec- 
trical voltage is generated. You will find more 
detail in Basic Electricity, NAVEDTRA 10086-B. 
Similarly, you will find simplified block diagrams 
to describe functional operations of the closely 
regulated power supplies that supply power to 
certain weapons and other electronic systems on 
modern ships. We will not attempt to show how 
individual circuits function. You will find in- 
formation on these circuits in Basic Electronics, 
Vol. 1, NAVEDTRA 10087-C, NavShips 
0967-000-0120, and individual manufacturer's 
technical manuals. 

VOLTAGE PRODUCED BY 

MAGNETISM 

Magnetic devices are used for thousands of 
different jobs. One of the most useful and widely 
employed applications of m agnets is the production 
of vast quantities of electric power from mech- 
anical sources. The mechanical power may be 
provided by a number of different sources, such 
as gasoline or diesel engines and water or 
steam turbines. However, the final conversion 
of these energy sources to electricity is done 
by generators which use the principle of electro- 
magnetic induction. We shall discuss the funda- 
mental operating principle of ALL such 
electromagnetic-induction generators. 

To begin, there are three fundamental con- 
ditions which must exist before a voltage can be 
produced by magnetism: 

1. There must be a CONDUCTOR in which 
the voltage will be produced. 



2 There must be a MAGNETIC FIELD to 
cut the conductor,, 

3 There must be RELATIVE MOTION between 
the field and the conductor. Either the conductor 
must be moved to cut across the magnetic lines 
of force, or the field must be moved to cut 
across the conductor. 

In accordance with these conditions, when a 
conductor or conductors move across a .magnetic 
field so that the lines of force are cut, electrons 
WITHIN THE CONDUCTOR are impelled in one 
direction or another. Thus, an electromotive force 
(emf) or voltage, is produced. 

In figure 2-1, note the presence of the three 
conditions needed to create an induced voltage: 

1. A magnetic field exists between the poles 
of the C- shaped magnet. 

2. There is a conductor (copper wire). 

3 There is relative motion. The wire is moved 
back and forth across the magnetic field. 

In figure 2-1A, the conductor is moving toward 
the front of the magnet (note the direction of 
motion) because of the mechanical force The 
right-hand end becomes negative, and the left-hand 
end becomes positive* The conductor is stopped 
in figure 2-1B. Motion in aliinnated (one of the 
three required conditions), and there is no longer 
an induced emf. Consequently, there is no longer 
any difference in potential between the two ends 
of the wire. The conductor in figure 2-1 C is 
moving away from the front of the magnet (motion 
reversed). An induced emf is again created. 
However, note carefully that the reversal of 
motion has caused a reversal of direction in 
the induced emf. 

If a path for electron flow is provided between 
the ends of the conductor, electrons will leave 
the negative end and flow to the positive end. 
As shown in figure 2-1D. Electron flow will 
continue as long as the emf exists. In studying 
figure 2-1, please note that the induced emf 



11 



SHIPBOARD ELECTRICAL SYSTEMS 



MAGNET 
MAGNETIC 




COPPER WIRE 
CONDUCTOR 




DIRECTION 
OF MOTION 




EMF 



NO 
MOTION 




INDUCED EMF 
REVERSED 




(C) 



MOTION 
REVERSED 




Figure 2-1 Q Voltage produced by magnetism a 



236.24 



could also have been created if the conductor 
were held stationary and if the magnetic field 
were moved back and forth. 

This basic principle will be used as we discuss 
the types of generators in this chapter* 



DIRECT CURRENT 
GENERATORS 

Various auxiliaries, amphibious and mine 
warfare ships, patrol landing and service craft, 
utilize d.c, generators as the main source of 
electrical power . A d.c a generator is a rotating 
machine which converts mechanical energy to 
electrical energy. Figure 2-2 shows an open- 
ended d.c. generator. A d.c. generator consists 
essentially of the following components: 

1. A steel frame or yoke containing the 
magnetic pole pieces and field windings. 



2. An armature consisting of a group of 
copper conductors, mounted in a slotted cylin- 
drical core, made up of thin steel disks called 
laminations, 

3 W A commutator to cause the current to flow 
in one direction through the external circuit 

4o Brushes with brush holders to carry the 
current from the commutator to the external 
load circuit., 

^ The d,c. generator must rotate at designed 
sfpeed to produce the designed voltage Thus 
any device that will cause generator rotation 
is commonly called a prime mover. One of the 
most common prime movers for d a c. generators 
is the diesel engine. Figure 2-3 shows a diesel- 
driven d c. generator 9 

The d.c, generator normally used on naval 
vessels is of stabilized shunt construction, which 
has inherently good voltage regulation. Basically, 
voltage regulation is the ability of a generator 



12 



Chapter 2 POWER SUPPLIES 



FIELD POLE 

a 

FIELD CORE 



YOKE 




BRUSHES 



COMMUTATOR 



ARMATURE 



Figure 2-2. Open- Ended d.c. generator. 



236.328(A) 



;o maintain a constant output (terminal) voltage 
mder varying loads. If closer regulation is 
squired, a voltage regulator will be utilized. 

A voltage regulator consists of a sensing 
levice and a mechanical or electrical control 
slement to produce changes in the generator 
leld current which are necessary to maintain a 
>redetermined constant generator terminal 
roltage. 



ALTERNATING CURRENT 
GENERATORS 

Alternating current generators, normally re- 
erred to as alternators, are used as the main 
source of electrical power on all combatant, 
ind many other types of Navy ships. With very 
ew exceptions these alternators are 450-volt, 
J-phase, 60-hertz machines. 



The alternators (a.c,) are smaller in size 
and have less weight that d.c. generators Main- 
tenance requirements are also reduced with a a c. 



CONSTRUCTION OF 

ALTERNATORS 

Alternators are usually of the d.c. excited 
rsvolving field type However, small alternators 
(25 kW and below) may be of the revolving 
armature type. Salient pole type rotors, which 
produce a rotating field, are used on alternators 
of 1800 rpm and below. (See figure ^2-4B.) 

An amortiseur (damping) winding is provided 
on salient pole rotors to dampen hunting effects 
when generators are operated in parallel and to 
equalize flux distribution when an unbalanced 
load condition exists. These windings are similar 
to a squirrel-cage and are placed near the pole 
face of each field pole. 



13 



SHIPBOARD ELECTRICAL SYSTEMS 




Figure 2-3. Diesel-driven d.c. generator. 



77.70 



The cylindrical rotor (fig. 2-5E) is a solid 
steel forging. Slots in which the fxeld coils a^t 
^bedded are milled into the forging. T^secoUs 
are usually arranged to form either two or four 
magnetic poles. The diameter of the rotor 

' 



*"***' ** vAa-gv^o W 1 LI1 el biD aJLl 

, ""' 7^ r t0r Iength is extended to obtain 
the required field strength. 

TYPES OF DRIVE 

Shipboard alternators are driven by steam 
turbines, diesel engines, or electric motors 
(Gas turbines are used in many of the newer 
installations.) The steam turbines norm ally ooer- 
ate at 12,000 rpm and drive the alternators 
through reduction gears. Turbine driven 400-Hz 
alternators, however, are usually directly con- 
nected to the turbine. 



14 



Engine-driven alternators are usually of the 
sahen pole type. The 60-H Z alternators are 
Erectly connected, while the 400-Hz installations 
are usually driven through step-up gears. 



r " dri H n altern ators are used to convert 
current to alternating current, or alterna- 
ting current of one frequency to alternating 
current of a different frequency "wrnanng 



60-HERTZ ALTERNATORS 



alternator shown in fig. 

*in Shlp ' s ^^vice alternators found 

aboard certain frigates. The alternator is rated 



Chapter 2 POWER SUPPLIES 



A. STATOR 




B. ROTOR 



139.43X 

Figure 2-4. Low- speed salient pole engine-driven 
alter nator 



at 450 volts and produces 750 kW, 3~phase, 60-Hz 
power at 1 200 rpm . The totally enclosed alternator 
(fig. 2-7) has a double-tube type air cooler located 
on top of the alternator stator. The stator (fig. 
2-8) has six temperature detectors embedded 
in the slots of the stator to monitor stator 
temperature during operation. Space heaters are 
located inside the stator on the lower part of 
the frame. These heaters prevent condensation 
of moisture on the windings during shutdown 
periods. 

The alternator rotor (fig. 2-9) is of the 
salient pole type. It has six poles and two 
bronze collector rings to apply the d.c. power 
(revolving d.c. field). As the turbine drives the 
rotor, the magnetic field of the rotor cuts the 
coils of the stator to produce a voltage in the 
stator. The electrical load is connected to the 
stator. 

400-HZ GENERATOR 

In modern-day electronics and computers, 
the need arose for miniaturization of equipment 




ROTOR 



139.44X 

Figure 2-5. High-speed turbine-driven 
alternator . 



in both aircraft and naval vessels. Experi- 
mentation with various frequencies showed that 
a 400-Hz system would meet these require- 
ments. A higher frequency will produce a higher 
speed, as well as a higher torque, for a given 
size motor. Therefore, a smaller size 400-Hz 
motor can be used without affecting the output. 
Experimental efforts proved that the 400-Hz 
system was unsatisfactory as the sole source 
of power for shipboard use. "This system was 
found to be impractical for large power appli- 
cations because of heat dissipation and voltage 
losses. The 400-Hz system is used in equipment 
that requires the higher frequencies and wherever 
the smaller motors are advantageous. The 400-Hz 
power supplies furnish power for systems such 
as the gyrocompass, radar, sonar, andfire control 
circuits. Since 400-Hz power is generated in the 
same manner as 60-Hz power, no attempt will 
be made to discuss the generation of 400-Hz* 



15 



SHIPBOARD ELECTRICAL SYSTEMS 



AC GENERATOR 

i 



REDUCTION 
GEAR 



TURBINE 




27.356X 



Figure 2-6. Turbine-Generator (alternator) set* 



A typical example of a 400-Hz system aboard 
ship is a 30-kW motor-generator set, 

30-kW MOTOR GENERATOR SET 

A typical closely regulated motor-generator 
set (fig 2-10), consists of a 450- volt, 3-phase, 
60-Hz, 50-hp, wound rotor induction motor which 
drives a 450-volt, 3-phase, 400-Hz, 30-kW gener- 
ator* The set is regulated and controlled by a 
voltage and frequency regulating system which 
is housed in the rotor resistor and regulator 
unit control cabinets and by a magnetic controller 
with associated pushbuttons and switches which 
are located in the control cabinet (fig. 2-10). 

The magnetic controller is a conventional 
across-the-line semiautomatic motor controller 
(starter). The voltage regulating system supplies 
the proper field current to the generator to 
maintain the generator output voltage to within 
1/2 of 1% of the rated output voltage for all 
load conditions. The frequency regulating system 
controls the speed of the drive motor to maintain 



the output frequency of the generator to within 1/2 
of 1% of its rated value for all load conditions. In 
addition, power sensing networks are included to 
eliminate speed droop with increased generator 
loads and to maintain equal sharing of the load 
between paralleled generators. 

VOLTAGE REGULATORS 



As previously described most d.c. generators 
have inherently good voltage regulation character- 
istics. Due to a.c tt characteristics alternators 
have poor voltage regulation,, To compensate for 
this disadvantage, a voltage regulator must be 
incorporated* There are several types of voltage 
regulators used in naval vessels (1) indirect 
acting rheostatic, (2) direct acting rheostatic, 
(3) rotary amplifier, and (4) combined static 
excitation and voltage regulation system all 
use the same basic principles. Voltage regulation 
is accomplished by controlling the amount of 
current in the generator field* In this chapter 
we shall give a basic description of the combined 



16 



Chapter 2 POWER SUPPLIES 



POLE 



COOLER 




!39o44X 

Figure 2-7. Turbine - Driven alternator 
(cooler shown). 




HEATERS 



Figure 2-8. Stator. 



27.85X 



COLLECTOR 
RINGS 




Figure 2-9 Salient pole rotor. 



27o86X 



static excitation and voltage regulation system 
which is being used on most new construction 
ship So 

COMBINED STATIC 
EXCITER AND VOLTAGE 
REGULATION SYSTEM 

The combined static ex dter and voltage regu- 
lation system consists of a (1) static exciter, 
(2) field flashing circuit, (3) automatic voltage 
regulator, and (4) manual voltage control. 

Static Exciter 

The static exciter, fig. 2-11 consists of a 
3-phase, bridge rectifier (CR1), three linear 
reactors (LI, L2, L3), and three saturable 
current potential transformers (SCPT) (Tl, T2, 
T3). Each SCPT has a current winding, a poten- 
tial winding, a secondary winding, and a control 
winding. These are connected in a 3-phase 
circuit, with the output of the secondary windings 
rectified and applied to the generator field. 

At no load, the input to the SCPT's is from 
the generator terminal voltage, through the poten- 
tial windings and linear reactors. 

Under load, the line current flowing through 
the current windings adds a component that is 
approximately proportional, in magnitude and 
phase angle, to the voltage in the generator. 

The control winding current changes the 
output of the SCPT by saturating the cores. 



17 



SHIPBOARD ELECTRICAL SYSTEMS 



ROTOR RESISTOR 
CABINET- 



CONTROL 
CABINET- 



REGULATOR UNIT 
CONTROL CABINET- 





I 

r >~ , if .-v*' isi 




MOTOR GENERATOR 



40.111 



Figure 2-10. Motor generator set with control equipment. 



Field Flashing Circuit 

Since the static exciter cannot supply field 
current until the generator voltage is built-up, 
the field flashing circuit provides for the initial 
voltage buildup. As part of the circuit, a small 
permanent-magnet alternator (PMA), which is 
driven by the prime mover, furnishes excitation 
current through rectifier CR 5 (fig. 2-12). 

As the generator starts to turn over, the 
PMA builds up an a.c. output which is rectified 
by the 3-phase full- wave-bridge rectifier CR5 
and furnishes d.c. to excite the generator field, 
thus building up a generator voltage. 

Automatic Voltage Regulation 

The static exciter will not supply the exact 
amount of field current required to maintain 
constant generator terminal voltage under all 
operating conditions because of: 

1 . The effects of a.c. generator field saturation 

2. Changes in field resistance because of heat 

3. Changes in ambient temperature 

4. Normal manufacturing tolerances 



Therefore, the direct-current supply to the 
control windings of the SCPT's is controlled by 
an automatic voltage regulator so that the gener- 
ator terminal voltage is held nearly constant. 

For explanation purposes the automatic voltage 
regulation system is subdivided as follows: 

1. Sensing circuit 

2. Reference circuit 
3 Comparison circuit 

4. Magnetic amplifier circuit 

5. Stabilizing circuit 

SENSING CIRCUIT. To obtain the best regu- 
lation during unbalanced load conditions, a sensing 
circuit (fig. 2-13) responds to the approximate 
average value of the three line voltages. This 
circuit consists of a 3-phase potential trans- 
former (T4), a rectifier (CR4), a reactor (L4), 
and a capacitor (Cl). 

Transformer T4 reduces the line voltage to a 
convenient value and rectifier CR4 converts the 
3-phase a.c. voltage to a d.c. voltage. If an 



18 



Chapter 2 POWER SUPPLIES 



r--~n 
i j^ | 






I PFN V 


i r~ T !ri 








lit i 

CURRENT WINDINGS i 
i ' 


r~ 
I 


"F 3 ~"| 


FIELD 
RI8 

H3- 

CRI 

k M ift Ml i 


i 




I 1 1 

u . .' 1 


i 




r" L ~~"i 


1 1 I 


i 




_| /Y L2^| 






I i 

I POTENTIAL WIN 


DINGS 
1 
1 
1 
1 
1 
1 
1 
, ' / 


ywvx. 
vvv-%_. 


J /"VVVN 1 

L J 


W T w 










1 \ ' 

! ! ~~ ! 


D 


I 




yn m Li 






SECONDARY WINDINGS 1 
1 1 1 


M|M 


FIELD 
RECTIFIERS 




II 1 " 






jOIhj! j[HSh|J 


|H 


WYxX. 




TO * 

ITOMATIC 
OLTAGE 

GULATOR 

<; 


1 CONTROL WINDINGS ' " 

1 ' II 

i 1 i J L_ 








TO 
LOAD 



Figure 2-11, Static exciter circuit. 



11.30 



unbalanced load condition causes the three line 
voltages to become unequal, the d.c. output 
of CR4 will have considerable ripple. Reactor 
L4 and capacitor Cl comprise a filter network 
which averages the varying d.c. output of CR4 
so that the voltage across Cl is essentially 
constant and is approximately the average of the 
three line voltages, 

REFERENCE CIRCUIT. The reference am- 
plifier (fig, 2-14) supplies a nearly constant 
reference voltage to the emitter of Ql in the 
comparison circuit. 



Rectifier CR2 consists of a zener diode, 
which is a rectifier that operates in the break- 
down (or zener) region and has a nearly constant 
11. 7- volt drop for a large variation in current. 

If the voltage applied to R5 and CR2 increases, 
the current increases, and the increase in voltage 
is absorbed as IR voltage drop across R5. The 
voltage across CR2 remains almost constant 
because of its flat voltage characteristic. 

COMPARISON CIRCUIT, The comparison 
circuit (fig. 2-14) compares the sensed voltage 



SHIPBOARD ELECTRICAL SYSTEMS 




/ 

\ , 


Ml iy 


Mm M i 


' I 




V 


Win iy i 






CR5 
(F2) (Fl) 

HMHBMHIBK . . * MHMMMMHI 



GENERATOR 
FIELD 

Figure 2-12. Field flashing circuit. 



11.30 



with the reference voltage by means of transistor 
Ql and acts on the magnetic amplifier to correct 
any difference. 

Resistors Rl, R2 (automatic voltage- control 
resistor) and R3 form a voltage divider. The 
voltage between the slider of resistor R2 (sensed 
voltage) and the negative side of CR4 is always 
proportional to the output of CR4 and to the 
average line voltage. 



SOURCE 




SIGNALyC! 



This sensed voltage is applied to the base 
of transistor Ql and the reference voltage is 
applied to the emitter. Whenever the sensed 
voltage is high, transistor Ql will be biased 
(turned) on, causing collector to emitter current 
to flow through magnetic amplifier control winding 
F2-F4, thereby phasing the magnetic amplifier 
on (saturating the core) which increases the 
gate winding current (A1-A2; B1-B2) in the 
magnetic amplifier. 

If the generator output voltage is low, the 
sensed voltage will be low, transistor Ql will 
be biased (turned) off, and no control current 
will flow in the control winding F2-F4 of the 
magnetic amplifier, which will operate in an 
unsaturated condition. This, in turn will raise 
output voltage. 

Voltage is adjusted by changing the position 
of the slider on the automatic voltage-control 
resistor R2. If the slider is turned toward 



11.30 



Figure 2-13. Sensing circuit. 



resistor R3, a smaller portion of CR4 output 
voltage is compared to the reference voltage, 
and the regulator acts to increase the line 
voltage as well as the voltage at the slider 
until the balance is restored. The line voltage 
is lowered by turning the slider toward resistor 
Rl. 



MAGNETIC AMPLIFIER CIRCUIT. Changes 
in the generator voltage produce changes in the 
current in the comparison circuit in the order 
of milliamperes. However, it is desirable to have 
these small current changes produce changes in 
the order of amperes in the control windings 
of the SCPT's. This is accomplished by using 
a magnetic amplifier (fig. 2-14) between the 
comparison circuit and the control windings 
of the SCPT's. 



20 



Chapter 2 POWER SUPPLIES 



TO EXCITER 
CONTROL WINDING 




FILTERED 
OUTPUT 
OF CR4 



MAGNETIC 
AMPLIFIER 



COMPARISON 
CIRCUIT 



SENSED 
VOLTAGE 



REF. 
CKT. 



Figure 2-14. Reference/Sensed Voltage /Comparison Circuit. 



11.30 



STABILIZING CIRCUIT. In any closed-loop 
regulating system containing more than two 



prevent this condition, a stabilizing circuit has 
been inserted between the field of the generator 



significant time constants and having relatively or exciter output and the comparison circuit. 



high gain, there can be a condition of sustained 



The elementary diagram for this stabilizing 



oscillations, sometimes called "hunting,," To circuit is shown in fig 2-15. Resistor Rll and 



C3A 



RI2B hHRI3A RI3B 




11.30 



Figure 2-15. Stabilizing circuit. 
21 



SHIPBOARD ELECTRICAL SYSTEMS 



capacitor C2 form a filter to remove the normal 
ripple from the exciter output voltage. Resistors 
R12 and R13 and capacitors C3 provide optimum 
system stability. 

Manual Voltage Control 

The generator output voltage can be controlled 
manually by manual voltage control rheostat 
R20 (fig. 2-16). 

Rectifier CR1 voltage (exciter output voltage) 
is applied to the SCPT control windings through 
manual control rheostat R20. An increase in 
R20 resistance decreases SCPT control current, 
which increases the exciter output voltage . 

SPEED REGULATION 

Speed regulation of the prime mover is needed 
on both a.c. and d.c. generators,. As load is 
applied to the generators, the prime movers 
tend to slow, thus changing the characteristics 
of the generator output. Although the Navy uses 
many types of speed regulators, we shall discuss 
only the newer type which is being installed 
on newly constructed vessels. 

ELECTROHYDRAULIC 
LOAD-SENSING SPEED 
GOVERNOR 

Electrohydraulic load- sensing speed gover- 
nors are used with ship's service generators 



in electrical systems which require closer fre 
quency regulation than that provided by mechanics 
type governors. Electrohydraulic governors hav 
met with great success on both steam-turbim 
and diesel-driven generators. 

An electrohydraulic governor may be operate 
as an isochronous governor (constant speed at a] 
loads) or with speed droop which permits par- 
alleling with other generators that have conven- 
tional fly- weight governors. 

Operation 

The steam valve or throttle that controls thi 
prime mover fuel supply is operated by ai 
electrohydraulic actuator which responds to th< 
output of a magnetic amplifier. Generator speet 
and load signals are fed into the transistor ampli- 
fier to produce a power output sufficient to 
operate the electrohydraulic actuator which cor* 
rectly positions the steam valve or throttle 

The speed signal is usually provided by i 
small permanent magnet generator driven fron 
the shaft of the prime mover or ship's service 
generator. The speed signal is sometimes ob- 
tained by sensing the output frequency of the 
ship's service generator, but the loss of signal 
in case of short circuit on the generator is 
disadvantage of this method. The speed signal 
is applied to a frequency sensitive circuit and 
to a reference circuit in the governor control 
unit. The output of this circuit is an erroi 



TO SCPT 
SECONDARY WINDINGS 



GENERATOR 
FIELD 



CRI 



TO CONTROL 
WINDINGS 
ON SCPT 



R20 



MANUAL 



Figure 2-16. Manual voltage control circuit. 
22 



11.30 



Chapter 9 POWER SUPPLIES 



signal if there is any deviation from rated speed. 
The error signal is applied to the transistor ampli- 
fier and acts to restore rated speedo Stability 
is obtained by the use of electrical feedback 
circuits. 

Load-measuring circuits are used in the 
electrohydraulic governor to obtain proper load 
ratio on each paralleled generator. Most governing 
systems are so designed that any change in 
load produces a signal which is fed into the 
transistor amplifier and acts to offset any antici- 
pated speed change due to load change. The 
load-measuring circuits on governors of all 
generators that operate in parallel are connected 
by a tie cable. The governor may be designed 
or preset so that each paralleled generator 
will equally share the total load, or a load ratio 
adjustment may be provided. Any deviation in 
proper load ratio produces a circulating current 
in the tie cable. The circulating current acts in 
the transistor amplifier circuit to increase or 
decrease fuel supplied to the generator prime 
movers until proper load ratio is achieved. 

The electrohydraulic load-sensing governor 
used in this discussion is made up of four 
major units (fig. 2-17) the EO-M control box, 
the load signal box, the EG-R hydraulic actuator, 
and the valve operator. 

The input signal (voltage) is proportional 
to the speed of the permanent magnet generator 
(PMG) and is applied to the EG-M control box 
(fig. 2-18). The control box compares this voltage 
with a reference voltage and, if there is a 
difference, supplies an output voltage to energize 
the EG-R hydraulic actuator. A pilot valve 
plunger in the actuator directs oil to or from 
a remote servo in the valve operator. The 
valve operator moves the mechanism to increase 
or decrease the steam, which returns the turbine 
speed to normaL 

The load signal box detects changes in load 
before they appear as speed changes and applies 
a proportional voltage to the EG-M control box. 
The load signal box detects these changes through 
the resistor box, which develops a voltage from 
the secondary of current transformers* This 
voltage is compared with the generator load 
output voltage and, if a difference exists, the 
load signal box applies a proportional voltage to 
the control box. 

The droop switch allows parallel operation 
with governors of types other than EG. The 



circuit breaker auxiliary contact provides a path 
for control load signals to other paralleled units. 



NO-BREAK POWER 
SUPPLY SYSTEM 

A no-break power supply system provides an 
uninterrupted electrical power supply which is 
relatively constant in voltage and frequency 
under all load conditions. The no-break power 
supply automatically takes over when the normal 
power supply is interrupted, off-frequency, or 
off- voltage o The no-break power supply system is 
presently being used by ships using the Central 
Operations Systems and by ships with equipment, 
control, or computer systems which need an 
uninterrupted electrical power supply for effective 
operation. 

The system uses a motor-generator set, 
batteries, and associated controls to provide 
its regulated output. Either unit of the motor- 
generator set can perform as a motor with the 
other as generator, thus permitting two modes 
of operation. 



MOTOR GENERATOR 
MODE 1 

In mode 1 operation of the motor-generator 
set (fig. 2-19A), the a.c. end of the set is driven 
from the ship's service power supply; the d.c. 
end is a generator providing power to the system 
batteries. This mode of the motor-generator 
operation exists when the ship's service power 
supply is meeting the voltage and frequency 
requirements of the critical load. 



MOTOR-GENERATOR 
MODE 2 

Mode 2 operation of the motor-generator 
set (fig. 2-19B) represents the condition by 
which the set receives power from the batteries, 
and the a.c. end of the set provides the power re- 
quirements for the critical load. Mode 2 is 
referred to as the Stop Gap Operation. 



STATIC POWER SUPPLIES 

Static power supplies using solid-state com- 
ponents are being used for many shipboard 



23 



SHIPBOARD ELECTRICAL SYSTEMS 





WSS538SSD 




EG-M CONTROL 
BOX 



LOAD SIGNAL 
BOX 




EG~R 
ACTUATOR 



VALVE 
OPERATOR 




111.150X 



Figure 2-17. Electrohydraulic load- sensing governor system components,, 



applications, specifically, 400-Hz equipment. We 
have already described an MG set which con verts 
60-Hz to 400-Hz. Static power supplies offer 
certain advantages over MG sets, such as lighter 
weight, smaller space requirements, and no 
moving parts, hence quieter operation, less 
maintenance, higher efficiency, and faster reac- 
tion time to transient disturbances. Static power 



supplies can be designed to change d.c. to a.c. 
a a c. to d c., or a.c. to a.c, of different frequencies. 

5 kW 250 VDC, 120 
VAC 400 Hz STATIC 
INVERTER 

The model 4345D Static Inverter (fig. 2-20) 
develops a closely regulated source of 400-Hz, 



24 



Chapter 2 POWER SUPPLIES 




REMOTE SERVO 

(VALVE 
OPERATOR) 



DROOP 
SWITCH 




RESISTOR 

BOX 

CIRCUIT BREAKER 
AUXILIARY CONTACT 




PARALLELING 

LINE 
TO OTHER UNITS 




SPEED SETTING 
POTENTIOMETER 












CRITICAL 
LOAD 

450 VAC 
3-PHASE 
60 HERTZ 


SHIP 450 VAC 










DmA/FD 3 HAot ' 
rUWtK cr\ WFRT7 

SUPPLY - 








< i 






DP 












r* 




n 


(AC 
MOTOR 


^ DC 
GENERATOR 


BATTERIES 



MOTOR- GENERATOR SET 
A MODE \ NORMAL OPERATION FROM THE NORMAL SUPPLY 



111.151 
Figure 2-1 8 Block diagram of the electrohydraulic load-sensing governor system. 

3-phase power from a 240 VDC source. We 
shall not attempt to cover the circuitry of this 
system in our discussion. One basic circuit will 
be used as an example of how the theory is 
possible. 

Basically, d.c. power is converted to a.c. 
power in the inverter sections by a rapid change 
in the direction of current flow through a trans- 
former. In figure 2- 21 A the main d.c. source 
is placed across the primary of a transformer. 
If switch SI is closed, a voltage is produced on 
the secondary of transformer Tl. When SI 
is reopened, the voltage decreases to zero. 
A similar action occurs if S2 is closed and 
reopened, but the voltage produced is of opposite 
polarity. Referring to figure 2-21B a square 
wave form would be produced. By timing the 
switching action and adding a filter (fig. 2-21C) 
to the secondary of Tl you can obtain a 400-Hz 
sine wave (fig. 2-21D). In the inverter, SI and S2 
are replaced by semiconductor devices. There are 
two inverters which operate 90 out of phase 
to produce a standard two-phase power. The 2- 
phase, sine- wave power is then converted to 
3-phase power by a SCOTT T-connected Trans- 
former. Detailed functions and test points should 











CRITICAL 
LOAD 

450 VAC 
3-PHASE 
60 HERTZ 


SHIP ^gQ VAQ 

SLRVICt -a PUAOC _ 










DOWPQ O-KMAbt 
rUWtn cr > UPDTT 
SUPPLY 60 HtRTZ . 














i 


, i 
















r~ 


4- 


~| 


AC DC 
GENERATOR | MOTOR 


BATTERIES 



MOTOR-GENERATOR SET 
B MODE 2 STOP GAP OPERATION FROM ASSOCIATED BATTERIES 



Figure 2-19. Block diagram of 
power supply. 



the 



77.297 
no-break 

25 



SHIPBOARD ELECTRICAL SYSTEMS 





OUTFIT 



V 


L 

A 
G 


SI CLOSED S' 

n 


1 OPENED 









TIME 



S1 




OUTPUT 



40.79X 



Figure 2-20. Static inverter,, 



be obtained from the manufacturers technical 
manual. 

150 kW 440 VAC 60-Hz, 
450 VAC 400-Hz STATIC 
CONVERTER 

Some newer ships are using a centralized 
400-Hz power supply to meet the ever-increasing 
400-Hz equipment demands. The newer DD's use 
a static power converter that produces an output 
of 450 VAC, 400 Hz, 3 phase at a maximum of 
150 kW continuous power , An input of 440 VAC, 
60-Hz, 3 phase is required (fig. 2-22) . 




TIME 



27.316 



Figure 2-21. Basic inverter. 



26 



Chapter 2 POWER SUPPLIES 




Teledyne Inet 187.5 KVA, 150 KW, 60 Hz to 400 Hz Power Converter 



Figure 2-22. Power converter assembly. 



27.315X 



The 150 kW converter works basically the 
same as the 5 kW model 4345D inverter, first 
changing the a.c. to d.c., then using the same 
basic switching action as the 5 kW inverter 
Note in figure 2-23 that the 440 VAC 60 Hz 
goes into the 60 Hz to DC CONVERSION FUNC- 
TION. This section converts the a.c. to approxi- 
mately 390 VDC. The LOW VOLTAGE POWER 

27 



DISTRIBUTION section provides low voltage 
power from the 440 VAC input to operate tran- 
sistors, logic circuits, and other integrated cir- 
cuits in the rest of the converter. The CONTROL 
FUNCTION provides signals that control the 
operation of the converter. Signals from other 
functions are processed to provide output voltage 
control signals and, in the event of faults, 



SHIPBOARD ELECTRICAL SYSTEMS 



I" 8&* <sa- 









CO CO CO 




10 








t: G z o 

s s 



PROTECTION 1 
BYPASS 


_ U. 

fe 











rl 

fi 

g 


o 

h 

0) 

I 

Pk 

d 





& 

8 

T( 

I 

D4 

s 

55 



28 



Chapter 2 POWER SUPPLIES 



TERMINAL 

BOARD 



CABINET 

ASSEMBLY 



CHASSIS 
ASSEMBLY 





HEAT SHIELD 
(SHOWN REMOVED) 



DOOR 
ASSEMBLY 



CIRCUIT 

CARD 

ASSEMBLY 



Figure 2-24, Line voltage regulator type 1ES25007 front views open and closed. 



111.102 



SHIPBOARD ELECTRICAL SYSTEMS 



SECONDARY 



INPUT 
o 



T! 
PRIMARY 



T2 



POWER 
THYRISTOR 



PULSE 
AMPLIFIER 



OUTPUT 

o 



ZENER 

REFERENCE 

CIRCUIT 



SYNCHRONIZED 

PULSE 
GENERATION 



t 



ERROR 

SIGNAL 

AMPLIFIER 



111.102 

Figure 2-25. Line voltage regulator simplified 
block diagram. 

to provide signals that automatically shut down 
the converter. The REFERENCE 400-HZ DE- 
VELOPMENT FUNCTION generates signals to 
drive the DC 400-HZ CONVERSION FUNCTION 
circuits. These signals are developed by a 
4800-Hz oscillator (pulse generator) whose fre- 
quency is controlled by a d.c. input. The DC 
TO 400-HZ CONVERSION FUNCTION contains 
the switching devices necessary to convert the 
d.c. to 400 Hz a.c. The frequency output is 
controlled by signals from the REFERENCE 
400-HZ DEVELOPMENT FUNCTION, and the 
voltage output is controlled by signals from the 
CONTROL FUNCTION. Because of the relatively 



high power output, a heat exchanger is incorpo- 
rated to provide cooling to the inductors, trans- 
formers, and rectifiers for each of the three 
phases. A continuous flow of seawater cools a 
closed fresh water system. The fresh water is 
circulated by a pump through the heat exchanger, 



LINE VOLTAGE REGULATORS 

Line voltage regulators are used on naval 
ships for equipment that requires closely regu- 
lated voltage under varying load conditions, 

There are several designs of line voltage 
regulators available. The basic operation de- 
scribed in the next section will cover a typical 
design. 

TYPE 1ES25007 LINE 
VOLTAGE REGULATOR 

The type 1ES25007 line voltage regulator 
(fig. 2-24) will maintain 114 V, 75 amp, 87 
kVA at 0.5%. Regulation is achieved by con- 
trolling a transformer directly in line with the 
load. The operation is designed around Thyris- 
tors, which control the primary of T-l. Thyris- 
tors are transistors which have a switching 
characteristic. 

A line voltage is sensed at transformer T-2 
(fig. 2-25) and compared with a zener diode 
network. Any error is then amplified and sent 
to the synchronized pulse generator which is 
designed to keep the error signal in phase with 
line voltage. The error signal then goes through 
a pulse amplifier which fires (switches) the 
Thyristors to either aid or buck the voltage 
at Transformer T-l. If sensed line voltage 
is suddenly increased, a buck signal is applied 
to T-l, tending to oppose this increase. If a 
reduction in line voltage occurs, an opposite 
action will take place 



30 



CHAPTER 3 

DISTRIBUTION SYSTEMS 



Chapter 2 dealt with different methods of 
snerating voltage using various types of equip- 
tent. In this chapter we shall discuss how this 
Dwer (generated voltage) is distributed on naval 
assels and how selective tripping is utilized. 
/e shall also discuss the devices used toaccom- 
Lish power distribution in a safe, reliable 
ad efficient manner. 

The a.c. power distribution system aboard 
lip consists of the a.c. power plant, the means 
> distribute the power, and the equipment which 
snsumes the power, such as lighting systems 
ad electric motors. The power plant is either 
le ship's service electric plant or the emergency 
lectric plant. The means of distributing the 
lip's service power is through load centers 
ad power panels. 



SHIP'S SERVICE POWER 
DISTRIBUTION 

Most a.c. power distribution systems in naval 
3ssels are 450-volt, 3-phase, 60-hertz, 3-wire, 
agrounded systems. 

The ship's service generator and distribution 
(vitchboards (fig. 3-1) are interconnected by 
as ties so that any switchboard can be connected 
> feed power from its generators to one or 
tore of the other switchboards. The bus ties 
Iso connect two or more switchboards so that 
le generator plants can be operated in parallel, 
he power distribution to loads can be from 
le generator and distribution switchboards or 
om switchgear groups to load centers, to 
Istribution panels, and to the loads, or directly 
*om the load centers to larger loads. 



EMERGENCY POWER 
DISTRIBUTION 

The emergency power distribution system 
ipplies an immediate and automatic source of 



electric power to a limited number of selected 
vital loads in the event of failure of the ship's 
service distribution system. This system, which 
is separate and distinct from the ship's service 
distribution system, includes one or more emer- 
gency distribution generators and switchboards. 
Each emergency switchboard (fig. 3-2) is supplied 
by its associated emergency generator. The 
emergency feeders run from the emergency 
switchboards and terminate in manual or auto- 
matic bus transfer equipment at the distribution 
panels or at loads for which emergency power is 
required. The emergency power distribution sys- 
tem is 450-volts, 3-phase, 60-hertz with trans- 
former banks at the emergency distribution 
switchboards to provide 120-volt, 3-phase power 
for the emergency lighting system. 

The emergency generators and switchboards 
are located separately from the ship's service 
generators and distribution switchboards. The 
emergency feeders are located near the center- 
line and higher in the ship (above the waterline) 
than the normal and alternate ship's service 
feeders. This arrangement provides horizontal 
separation between the normal and alternate 
ship's service feeders and vertical separation 
between these feeders and the emergency feeders, 
thereby minimizing the possibility of damaging 
all three types of feeders simultaneously. 

The emergency switchboard is connected by 
feeders to at least one and usually to two 
different ship's service switchboards (fig 3-3). 
One of these ship's service switchboards is the 
normal source of ship's service power for the 
emergency switchboard and the other is the 
alternate source. The emergency switchboard and 
distribution system is normally energized from 
the normal, or preferred source of ship's service 
power. If this source of power should fail, bus 
transfer equipment automatically transfers the 
emergency switchboard to the alternate source 
of the ship's service power. If both the normal 



31 



SHIPBOARD ELECTRICAL SYSTEMS 



X 

CO 
CD 




CD 
O 



CD 
CO 






CO 

0> 

3, 



32 



Chapter 3 DISTRIBUTION SYSTEMS 




77.166X 



Figure 3-2. Emergency switchboard. 



and alternate source of ship's service power 
fails, the emergency generator will start auto- 
matically within 10 seconds after power failure 
and the emergency switchboard will automatically 
transfer to the emergency generator. 

CASUALTY POWER 
DISTRIBUTION SYSTEM 

Damage to ship's service and emergency 
distribution systems during wartime led to the 
development of the casualty power system. The 



casualty power distribution system provides for 
making temporary connections (runs) to vital 
circuits and equipment (fig. 3-4). The system 
is limited to only those facilities necessary 
to keep the ship afloat and to permit the ship 
to get out of the danger area. The system also 
supplies a limited amount of power to armament, 
such as antiaircraft guns and their directors 
to protect the ship when in a damaged condition. 
Optimum continuity of service is ensured 
in ships provided with ship's service, emergency, 



SHIPBOARD ELECTRICAL SYSTEMS 



;So 



r 



i\ 





1 ! 


1 


ri i 


1 


T i ' 


1 . 


> ' L^ 


1 < 

1 


} 1 


1 


1 1 


Ico^ 


1 


1 


1 


lo 


CD 


O 
lUJ 


T 
CJ 

in 


,co 






/"""N A _->/ 


! UJ * 




|O 


^A 


Iw 




IQ. 




fl 


i 


\ 




!-f 

li 


h 




CD 


.0 


CM 


<UJ 


tf) 


|CO 


HOi^A, , 


ILJ 


> ^ 


1 


< 


IQ: 


i 


,UJ 

Ico 


IO 


,QL * 




,x 




to 




1 ( 


1 


I 


>! 




_j f- 




l 




l /- 



Z*7 




en 
a: 



(T 
CD 



O 
QC 

O 



O 

o 
cc 

UJ 



O 

Q 
oj 

a 
o 

S 
1 



H 

4-> 

<D 
O 



O 



JH 
--> 
QQ 

r-4 

*a 



CO 
CO 



O DO 
2(7) h- 



34 



Chapter 3 DISTRIBUTION SYSTEMS 



FRAME 120 




PORTABLE CABLE 



/-BULKHEAD 
/ TERMINAL 



-FRAME 105 

2ND. DECK 




FRAME 90 



AFT 



-FIXED CABLE 



WATERTIGHT 
BULKHEAD 



3RD. DECK 



FWD 




V 



LOAD 




D- 



LEGEND 

BULKHEAD 
TERMINAL 

RISER 
TERMINAL (R.T.) 



CONNECTION 
TERMINAL (C.T.) 



Figure 3-4. Typical power run. 



103.140 



I casualty power distribution systems. If one 
terating plant fails, a remote switchboard 
L be connected by the bus tie to supply power 
m the generator or generators that have not 
led. 

If a circuit or switchboard fails, the vital 
ds can be transferred to an alternate feeder 
. source of ship's service power by means of a 
nsfer switch near the load. 
If both the normal and alternate sources of 
ship's power fail because of a casualty to 
generator, switchboard, or feeder, the vital 
iliaries can be shifted to an emergency feeder 
t receives power from the emergency switch- 
rd. 

If the ship's service and emergency circuits 
, temporary circuits can be rigged with the 
ualty power distribution system and can be 
d to supply power to vital auxiliaries if any 
the ship's service or emergency generators 
be operated. 



The casualty power system includes suitable 
lengths of portable cable stowed on racks through- 
out the ship. Permanently installed casualty 
power bulkhead terminals form an important 
part of the casualty power system. They are 
used to connect the portable cables on opposite 
sides of bulkheads, so that power may be trans- 
mitted through compartments without loss of 
watertight integrity; also included are perma- 
nently installed riser terminals between decks 
(fig. 3- 5 A). The vital equipment selected to 
receive casualty power will have a terminal box 
(mounted on or near the equipment or panel con- 
cerned) connected in parallel with the normal 
feeder for the equipment. 

Sources of supply for the casualty power 
system are provided at each ship's service 
switchboard and emergency generator switch- 
board (fig. 3-5B). A casualty power terminal is 
installed on the back of the switchboard, or 
switchgear group, and connected to the bus 
ties through a 225- or 250-ampere AQB circuit 



SHIPBOARD ELECTRICAL SYSTEMS 





Figure 3-5. Casualty power terminals. 



77.257 



breaker. This circuit "breaker is connected be- 
tween the generator circuit breaker and the 
generator disconnect links so, that by pulling 
the disconnect links, the generator may be 
isolated from the switchboard and may be used 
exclusively for casualty power purposes, if 
desired. 

Due to the inherent dangers of electric shock 
involved with the rigging of casualty power 
cables, you, as division officer or electrical 
officer, should be thoroughly familiar with Nav- 
Ships Technical Manual Chapter 9880 Section 
El, Engineering Damage Control, and the casualty 
control manual for your ship. 



SWITCHBOARDS 

The a.c. switchboards may consist of a 
single section or of several sections physically 



separated and connected by cables to form a 
switchgear group* This arrangement of sections 
provides greater resistance to damage caused 
by shock and also provides a means to localize 
damage and to remove damaged sections for 
repairs or replacement. 

The ship's service switchboard (fig. 3-6) 
is housed in sheet-steel panels or enclosures 
from which only the meters and ope rating handles 
of the switches and circuit breakers protrude 
to the front of the switchboard. This type of 
construction is used for all a.c. distribution 
systems and for the d.c. distribution systems 
in some large ships. (Compare the ship's service 
switchboards shown in figures 3-1 and 3-6. 
Although there is a variety of designs for these 
switchboards depending on the needs of the ship, 
the switchboards basically function in the same 
manner.) 



36 



Chapter 3 DISTRIBUTION SYSTEMS 




77.166 



Figure 3-6. Ship's service switchboard. 



The switchboard equipment is grouped to 
form a number of units, each unit complete 
with a separate front panel and all the required 
devices such as controls on the a.c. generator 
control unit. In addition, there is an a.c. bus tie 
unit, a power distribution unit, and a lighting 
distribution unit. A number of units mounted 
on a common base comprise a section or several 
sections which may be physically separated 
and connected by cables to form a switchgear 
group. 

CIRCUIT BREAKERS 

Circuit breakers have three fundamental pur- 
poses: they provide circuit protection; they per- 
form normal switching operations; and they 



isolate a defective circuit while repairs are 
being made. 

Air circuit breakers are used in switchboards, 
switch gear groups, and distribution panels. 
The types, labeled according to size, on naval 
ships are ACB, AQB, AQB-A, AQB-LF, NQB-A, 
ALB and NLB. They are called air circuit breakers 
because the main current-carrying contacts in- 
terrupt in air. 

Circuit breakers can be manually or elec- 
trically operated. Some types may be operated 
both ways, while others are restricted to one 
mode. 

Some larger circuit breakers have a drawout 
feature (fig. 3-7) which allows the electrician's 



37 



SHIPBOARD ELECTRICAL SYSTEMS 





IN NORMAL POSITION 



B 

IN WITHDRAWN POSITION 



Figure 3-7. Large circuit breaker (ACB-1600). 



77.258(.259) 



mate to perform maintenance, tests and in- 
spections with greater ease. Smaller breakers 
(fig. 3-8) can be removed from the switchboard 
by loosening the mounting screws and pulling 
the breaker from the board. 

An explanation of different circuit breakers 
will not be complete without including a brief 
description of selective tripping features and 
their uses. 



Selective Tripping 

Selective tripping of circuit breakers permits 
isolation of a faulty section of the system and, 
at the same time, maintains power to as much 
of the system as possible. Selective tripping 
(coordination of the time-current characteristic 
of circuit breakers) is normally obtained by a 
mechanical, short time-delay feature of the 
circuit breakers so that the breaker closest 



to the fault will open first, and the breaker 
farthest from the fault and closest to the generator 
will open last. 

The short time-delay feature can be varied 
with limitations. The generator circuit breaker, 
which is closest to the power source, has the 
maximum continuous cur rent- carrying rating, 
the highest available short-circuit current rating, 
and the maximum short time-delay trip to ensure 
that the generator breaker will be the last 
breaker to trip. However, the generator breaker 
will trip, within the tolerance of the breaker, on 
the generator short circuit current at some 
definite interval of time. 

A portion of a distribution system with circuit 
breakers employing selective tripping is illus- 
trated in figure 3-9. The so-called instantaneous 
tripping time is the minimim time required for 
a breaker to open and clear a circuit when the 
operation of the breaker is not intentionally 



38 



Chapter 3 DISTRIBUTION SYSTEMS 




OPERATING HANDLE SHOWN 4. COVER SCREWS 

IN LATCHED POSITION 

AMPERE RATING MARKER 5. BREAKER NAMCPLATE 

MOUNTING SCREWS 6. COTTER KEY HOLE 

77.241 

igure 3-8. -Complete front view of an AQ3-A250 
circuit breaker. 



elayed. Each circuit breaker will trip in less 
lan 0.1 second (almost instantaneously) when 
le current exceeds the instantaneous trip current 
etting of the breaker. In a shipboard selective 
ripping power system the individual circuit 
reakers (generator, bus tie, shore power or 
seder breakers) differ from each other depending 
n: 



1. The available load current 

2. The available short circuit current 

3. The tripping time band and trip current 
settings selected 

Bus tie circuit breakers are usually set to 
:ip after a prescribed time delay (less than 
le generator circuit breaker time delay), at a 
urrent that is nearest to, but not less than 
50% of the bus tie breaker coil rating (for 



multigenerator switchgear groups) or at a current 
nearest to, but not more than 80% of the generator 
breaker short time-delay setting (for single 
generator switchgear groups). Instantaneous trip- 
ping is not normally used on bus tie circuit 
breakers. 

For currents less than the instantaneous trip 
current setting, the circuit breakers for selective 
tripping are constructed to cause an intentional 
delay in the operation of the breaker. The tirnv? 
delay is greater for small currents than for 
large currents and is therefore known as an 
inverse time delay. The current that will trip 
the AQB load circuit breaker instantaneously and 
clear the circuit will not trip the ACB feeder 
circuit breaker unless the current flows for a 
greater length of time. The same sequence 
of operation occurs for the other groups of 
circuit breakers in the system which are adjusted 
for selective tripping. The difference between the 
tripping times of the breakers is sufficient to 
permit each breaker to trip and clear the circuit 
before the next breaker starts to operate. 

Assume that a fault or defect develops in 
the cable insulation at point A (fig. 3-9) and 
allows an overcurrent to flow through the AQB 
load circuit breaker and the ACB feeder circuit 
breaker. The AQB load breaker will open the 
circuit and interrupt the current in an interval 
of time that is less than the time required to 
open the ACB feeder circuit breaker. Thus, 
the ACB feeder breaker will remain closed when 
the AQB breaker clears the circuit. However, 
if the fault current should exceed the interrupting 
capacity of the AQB load breaker (for example, 
an excess of 10,000 amperes), this breakerwould 
be unable to interrupt the fault current without 
damage to the breaker. To prevent damage to the 
AQB load breaker, the ACS feeder breaker (on 
switchboard IS) serves as a BACK UP breaker 
for the AQB load breaker and will open almost 
instantaneously. 

A fault at point B with overcurrent would 
trip the ACB feeder breaker in time but not 
the ACB generator breakers or bus tie breakers, 
which require longer time intervals in which 
to trip. A fault at point C with overcurrent would 
trip both ACB bus tie breakers. A fault at D 
with overcurrent on switchboard IS would trip 
the associated ACB generator breakers. In each 
case, the faulty section of the system is isolated, 
but power is maintained to as much of the system 
as possible with respect to the location of the 
fault. 



39 



SHIPBOARD ELECTRICAL SYSTEMS 



1SG 
GENERATOR 



1S 
SWITCHBOARD 



TYPE ACB ox 

FEEDER BREAKERS ) 




2SG 
GENERATOR 



YPE ACB GENERATOR 
BREAKERS 



TYPE ACB BUS TIE 
BREAKERS 



-X- 



-X- 



SHORE POWER 




TYPE AQB 

LOAD 
BREAKER 



TO LOAD 



Figure 3-9. Selective tripping of circuit breakers. 



77, 



Tl^e attainment of selective tripping requires 
careful coordination of time- cur rent character- 
istics fQr the different groups of circuit breakers. 
For example, if the system illustrated in figure 
3-9 is operating split plant (bus ties open) and 
if the time-current characteristics of the ACB 
feeder breaker and the ACB generator breaker 
were interchanged, a fault at B with overcurrent 
would trip generator iSG.off the line but would 
leave the feeder connected to the switchboard. 
This action would disconnect power to all equip- 
ment supplied by switchboard IS and also would 
not isolate the faulty section. Therefore, NO 
UNAUTHORIZED CHANGES should .be made to 
circuit breaker trip settings because these 
changes may completely disrupt the scheme 
of protection based on selective tripping. 

A circuit breaker should NEVER be removed 
from a switchboard without prior approval of 
the electrical or engineer officer, and then only 
after a thorough review of the applicable technical 
manual, and Chapte/ 9600 of NavShips Technical 
Manual. 

You should NEVER work on any circuit 
breaker, regardless of type, until you ensure 



that the circuit is open. Remember that cert; 
terminals may have voltage applied to them -si 
though the breaker is open. Aboard ship, pOY 
may be supplied to either end of the circ 
breaker. 

BUS BARS 

Bus bars (fig. 3-10) are heavy, rugged metal 
conductors usually insulated with a nonconduct: 
paint and are used to carry the large general 
loads within the switchboards. 

DISCONNECT .LINKS 

Disconnect links (fig. 3-11) are devices us 
in switchboards to isolate a generator, a switc 
board section or a bus tie whenever equip mt 
has been damaged or whenever maintenance 
required. 

Disconnect links are connected in the lar 
bus bars and are designed to carry the enti 
current of the bus. 



40 



Chapter 3 DISTRIBUTION SYSTEMS 



BUS BARS 




BUS BARS 



Figure 3-10. Opened rear view of ship's service switchboard. 



27.353X 



When work is to be performed on a circuit 
eaker, the disconnect link is opened. However, 
>u must remember that control power in MOST 
stallations will still be available at the circuit 
'eaker; therefore, the fuses for these devices 
list be pulled before you start to work. These 
ses are usually located on the back of the 
fitchboard and are readily accessible. 

The screw-type disconnecting links (fig. 3-12) 
e normally located in the rear of the switch- 



board and are operated by means of an insulated 
wrench. The disconnect links must be tightened 
firmly in both the * ' open' ' and " closed' 'positions. 
CAUTION: Do NOT operate a disconnect link 
when there is current flowing through the link. 

MONITORING DEVICES 

Watch stander s must have the ability to monitor 
the equipment for which they are responsible. In 



41 



SHIPBOARD ELECTRICAL SYSTEMS 




HINGE 
BLOCK 



CROSS-HEAD 
PIN 




BACKING 
PLATE 



LOCKING 
SPRING 



CONTACT 
BLOCK 



INSULATED 
BASE 



77.2 



Figure 3-11. Disconnect links. 



the electrical distribution system nany of the 
monitoring devices are located on the switch- 
boards. Meters, located on the face of the 
switchboard, (fig. 3-13) monitor speed (fre- 
quency), voltage, amperage, phase and speed 
relation (synchroscope) of two generators being 
paralleled. Indicator lights for ground detection 
and breaker position are also located on the 
switchboard. 

CONTROL DEVICES 

Switchboards also contain the devices neces- 
sary to control the speed of the prime mover 
(frequency) and the voltage. 

The speed of the prime mover (either diesel, 
steam turbine, or gas turbine) is controlled by 



a switch, located on the front of the switchboart 
which operates a governor motor located c 
the prime mover. 

The voltage is controlled by turning a sma 
rheostat, located on the switchboard, which inserl 
or removes resistance in the voltage reg^latoi 

PROTECTIVE DEVICES 



i 
i 
t 
1 
c 



c 

3 

Along with the previously discussed trippin a 
devices incorporated in the circuit breaker* 
the switchboard contains other safety and pro 
tective devices. a 

s 

On ships with a.c. ship's service powe t 
systems where the generators are operate 1 



42 



Chapter 3 DISTRIBUTION SYSTEMS 




- DISCONNECT LINKS 



Figure 3-12.- Rear view ship's service switchboard. 



77.256X 



)arallel, each generator control unit has a 
3rse power relay. The relay should trip 
generator circuit breaker in approximately 
ieconds with reverse power equal to 5 percent 
le generator rating. 

Reverse power relays trip the generator 
:uit "breaker to prevent motoring the generator. 
3 protection is provided for the prime mover 
its generator. 

n motoring, the faulty generator set will 
as an additional load for the good generator 
Motoring can result from a deficiency in 
prime mover input to the a.c. generator. 
j deficiency (insufficient torque) can be caused 



by loss of steam or low steam to the turbine, 
lack of fuel to the diesel engine or gas turbine, 
or other factors which affect the operation of the 
prime mover. In the absence of reverse power 
protection, when the input to the generator 
falls below that needed to maintain required 
generator speed, power is taken from the ship's 
service power system, and the generator acts 
as a motor driving the prime mover. 

Fuses are used to protect the monitoring 
and control devices. 

SHORE POWER 
CONNECTION 

The number and locations of shore power 
connections vary on different types of ships. 



43 



SHIPBOARD ELECTR5CAL SYSTEMS 





27.35 



Figure 3-13* Typical meters on switchboards. 



Shore power connections are provided at, or 
near, a suitable weather-deck location to which 
portable cables from the shore or from ships 
alongside can be connected to supply power 
for the ship's distribution system when the 
ship's service generators are not in operation. 

Shore power connections are connected to 
cables which terminate at circuit breakers located 
on the switchboards. A typical arrangement for 
shore power circuit breakers on smaller vessels 
is shown in figure 3-9. 



BUS TRANSFER 
EQUIPMENT 



Bus transfer equipment is installed on switch- 
boards, at load centers, distribution panels, or 



on loads that are fed by both normal and alternat 
and/or emergency feeders. See fig. 3-14. Thl 
equipment selects either the normal or alternat 
source of the ship's service power, or obtain 
power from the emergency distribution systen 
if an emergency feeder is also provided. 

Automatic bus transfer (ABT) equipment 1; 
used for loads that require two power supplies 
except for cold-ship starting of auxiliaries an 
fire pumps, which have manual bus transfe 
equipment. On the steering power equipment 
which is provided with a normal, alternate, an 
emergency power supply either automatic 01 
manual bus transfer equipment is used to selec 
between the normal and alternate supplies* Th( 
automatic bus transfer equipment is used t 
select between the ship's service and emergenc] 
supplies. On some ships only two sources o: 
steering power are provided normal and emer- 
gency. 



Chapter 3 DISTRIBUTION SYSTEMS 




AST 



Figure 3-14. Emergency switchboard (showing ABT's). 



77.324X 



LOAD CENTERS AND 
POWER PANELS 

Load centers and power panels are supplied 
om the switchboard, which is a branching out 
r the electric power distribution system. Power 
riginates at the power supply (fig. 3-15) and 
isses through a generator circuit breaker lo- 
tted in the main switchboard. On larger ships 
>wer can go to load centers (fig. 3-16) for further 
stribution to loads. Smaller ships usually in- 
>rporate the load centers as a part (sometimes 



called switchgear groups) of the main switchboard 
(fig. 3-17). Figure 3-18 shows a typical power 
panel. 



INTERIOR COMMUNICATION 
DISTRIBUTION 

Shipboard interior communications (1C) sys- 
tems are defined as anything that causes an 
audible or visual signal to be transferred within 



SHIPBOARD ELECTRICAL SYSTEMS 




SOME 
LARGER 
LOADS 



LOAD CENTER 



POWER PANEL 




LOADS 



MAIN 
SWITCHBOARD 



LOAD CENTER 



POWER PANEL 



Figure 3-15. Line diagram of power distribution (larger ships). 



27.61 



or between the compartments of a ship. They 
provide a means of exercising command within 
a ship and include voice interior communications, 
alarm, warning, ship control, entertainment, 
gyrocompass, and plotting systems. Although 
many of the weapons and fire control circuits 
are supplied by the 1C switchboards, these 
systems are not part of the 1C responsibility. 



1C SWITCHBOARD 



The 1C switchboard is the nerve center of 
the interior commani cations system. All interior 
communication and some fire control circuits, 
including fire control electronic systems, are 
energized through the 1C switchboard, 

To obtain maximum protection, most 1C 
switchboards are installed below the waterline 
and are energized from a normal, an alternate, 



and an emergency power supply to ensure con- 
tinuous service. 

In large combatant ships there are two mail 
1C switchboards. One switchboard is locatec 
in the forward 1C room, and the other switch- 
board is located in the after 1C and gyro room, 
Thus, each system or equipment receives its 
normal supply from the nearer 1C switchboard 
The after main 1C switchboard is usually arrangec 
similarly to the forward main board, except tha ( 
in the after 1C room some of the special busef 
such as the controlled-frequency bus may & 
omitted. 

In the older ships, separate 1C and actior 
cutout (ACO) switchboards are installed. In nev 
construction ships, 1C switchboards are composed 
of power control distribution and ACO sections, 

The latest type 1C switchboard is the front- 
service 1C board (fig. 3-19) which is constructed 
so that installation, operation, and maintenance 



46 



Chapter 3 DISTRIBUTION SYSTEMS 




77.166X 



Figure 3-16. Load center switchboard. 



an be accomplished entirely from the front of 
le switchboard. The front-service design uses 
box-type construction with hinged front panels, 
witches and fuse holders up to 60-ampere 
apacity and other relatively light items are 
lounted on the hinged panels, while heavier items 
re mounted behind removable panels. 

Terminal boards within the switchboard en- 
losure provide for termination of all ship's 



cables except for a few of the larger cables, 
which run directly to their associated switches 
and fuse holders. All wiring between the terminal 
boards and the equipment mounted on both the 
hinged and stationary panels is installed by the 
switchboard manufacturer to permit free swinging 
of the panels without interference from, or 
damage to, the wiring harness. 

To reduce the rigidity of the switchboard 
and to permit separate movement of panels 



SHIPBOARD ELECTRICAL SYSTEMS 




LOADS 



MAIN SWITCHBOARD 



27.66 

Figure 3-17. Line diagram of power distribution 
(smaller ship). 

during shock, cables are used instead of horizon- 
tal buses for connections between or among 
switchboard sections. Some vertical buses may 
be used, however, to supply sections of the 
individual panel. 

The principal advantage of the front- service 
1C switchboard is that it can be mounted against 
a bulkhead because no access space is required 
in the rear of the board. This feature results 
in a saving of space, which is most important 
aboard ship. 

The action cutout (AGO) section permits 
isolation of various portions of 1C systems 
and in addition, allows transfer control of certain 
systems from one station to another. Separate 
switchboards are usually provided for specialized 
systems such as the sound-powered telephone 
system. 

In older combatant vessels the ACO switch- 
board (one or more sections) is located in the 
central section, which also functions as damage 
control central. On new construction ships, 
damage control central is combined with engi- 
neering central (log room) and is located nearer 
to the engineering plant and farther from the 
1C room. However, the ACO section is located 
in the 1C room and is part of the 1C switchboard. 

A front-service ACO section is shown in 
figure 3-20. Drawout switch units are utilized 
with each unit ..^eorporating the associated fuse 
holders and overload indicators. 




27.355 



Figure 3-18. Typical power panel. 



1C SWITCHBOARD 
POWER SUPPLY 

The power distribution systems and arrange- 
ments of buses of 1C switchboards vary widely 
in different ships, dependent of the size and 
mission of the ship, the main power system, 
and the fire control (FC) system. The following 
discussion describes the general principles of 
a typical 1C switchboard power supply. 

The forward main 1C switchboard is supplied 
with power from as many sources as possible, 
The power supply usually consists of (1) a 
normal supply from a main power distribution 



Chapter 3 DISTRIBUTION SYSTEMS 



AUTOMATIC BUS TRANSFER 




27.270 



Figure 3-19. Front-service main 1C switchboard. 



iwitchboard of the forward machinery group, 
2) an alternate supply from a main power dis- 
ribution switchboard of the after machinery 
;roup, and (3) an emergency supply from the 
earer emergency-distribution switchboard. 

The normal 3-phase, 450- volt, 60- Hz power 
upply is obtained from the forward main ship's 
ervice distribution switchboard through an ACB 
ircuit breaker on that board. The 450-volt supply 
3 connected to a 450-volt bus on the main 1C 
witchboard through the bus-transfer switch 
\BT), as shown in figure 3-14. 

The 450-volt bus energizes the various 450- 
olt, 60-Hz circuits through individual switches 



and fuses. In this installation the 450/120-volt 
60-Hz transformer bank is energized directly 
from the 450-volt bus through fuses. However, in 
some installations the transformers are energized 
through a switch and fuse combination. 

The 1C transformer bank is connected delta- 
delta in order to operate open-delta in case of a 
casualty to one transformer (discussed in chapter 
5 of this training manual). When operating open- 
delta, strip the switchboard of all but the vital 
circuits. The load can be reduced as necessary 
by opening the switches of less essential circuits. 

In some ships in which the emergency power 
is extremely small, the main 120-volt a.c. bus 



49 



SHIPBOARD ELECTRICAL SYSTEMS 





Figure 3- 20. -Front view of front-service switchboard. 



55.311 



.*& tfZ% l FFS?Zi ?> contactors open automatic^ upon tra^e, 

srigf s sru s to to ^SLSS Sr^^ssa.^; s-ss 
. to* ~i BW1 o h e 9 "jss; Js^stg^^jsssssR 



Chapter 3 DISTRIBUTION SYSTEMS 



l-l(|)-450/l20V-60 r b 
TRANSFORMER 



ALT. PWR SUPPLY 
I20V-60O-I(1) FROM 




1.1.1 1.1 




Figure 3-21. Local 1C switchboard. 



140.18 



1C and FC buses have been opened to reduce section may be supplied by a motor generator 

load, the contactors supplying these buses or a static power supply which receives its power 

closed again. from the 450-volt, 60-Hz bus at its associated 

There are two 400-Hz closely regulated bus switchboard. The 120-volt, 400-Hz section of 

tions 450-volt and 120-volt. The 450-volt each switchboard receives its power from a 



51 



SHIPBOARD ELECTRICAL SYSTEMS 



delta-delta connected bank of transformers, which 
are connected to the respective 450-volt, 400 Hz 
sections. A d.c. section receives its power supply 
from a 120-VDC rectifier. 

LOCAL 1C 
SWITCHBOARDS 

A local 1C switchboard is usually provided 
in each engineroom to energize local 1C circuits. 
The normal supply for each switchboard is from 
the nearer main 1C switchboard. The emergency 
supply for each switchboard is from a local 
emergency lighting circuit. This arrangement 
provides the switchboard with the same power 
backup as that of the main 1C switchboard. 
However, in case of loss of power at the main 
1C switchboard or damage to the connecting 
cable, the local switchboards can still be energized 
from an alternate source. Automatic bus transfer 
switches are provided on the 1C switchboards in 
the engineroom and steering gear room on 
newer ships to minimize interruptions if the 
normal power source is lost. Action cutout 
switches are provided to disconnect equipment 
that is connected to local transmitters. 

A local 1C switchboard (fig. 3-21) is usually 
installed in each steering gear room to energize 
all circuits associated with steering-order and 
rudder-angle indicator systems. The normal 
supply for this switchboard is from the steering- 
power transfer switchboard through a local trans- 
former. An alternate supply is taken from a 
local emergency lighting circuit to provide power 
if the normal supply is lost. 

CLASSIFICATION 
OF CIRCUITS 

1C circuits are classified according to im- 
portance and to readiness. 

Each 1C circuit is classified into one of the 
following three groups according to its im- 
portance. 



VITAL CIRCUITS are those circuits th 
are essential to the fighting effectiveness 
the ship. The loss of a vital circuit, such; 
the gyrocompass system, would seriously irnpa 
fighting effectiveness. 

SEMIVITAL CIRCUITS are those circui 
that are very important but not essential 
fighting effectiveness. The loss of a semivit 
circuit, such as the auxiliary battle telepho 
system, would impair fighting effectiveness le 
than the loss of a vital circuit. 

NON VITAL CIRCUITS are those circuits tt 
are not essential to fighting effectiveness. T 
loss of a nonvital circuit, such as the boile 
feed signal system, would not impair fighti 
effectiveness. 

Each 1C circuit is classified into one oft 
following four groups according to its reading 

CLASS 1 CIRCUITS are those that are esse 
tial to the safety of the ship. These circuits a 
energized at all times. 

CLASS 2 CIRCUITS are those that (along ^ 
class 1 circuits) are essential to ship contK 
These circuits are energized during the prep; 
ration period for getting underway, while stand! 
by, while underway, and until the ship is seem 
after coming to anchor. 

CLASS 3 CIRCUITS, or BATTLE CIRCUIT 
are those that (along with class 1 and class 
circuits) are essential to complete interior co: 
trol. These circuits are energized during co: 
dition watches. 

CLASS 4 CIRCUITS are the convenience ci 
cuits that are energized only when require 
such as ship's entertainment system. 

Supply switches on 1C switchboards are colon 
as shown to identify readily the class of circui 

Class 1. . .Yellow continuously energized 

Class 2. . .Black underway circuits 

Class 3. . .Red battle circuits 

Class 4. . .White convenience circuits 



52 



CHAPTER 4 



MOTORS AND CONTROLLERS 



Electric motors and controllers are a vital 
rt of a ship's operating ability. They provide 
3 mechanical power for many purposes ranging 
Dm large horsepower pumps and compressors 

small fractional horsepower motors for fans 
d portable tools Most electric motors are 
nnected to the power supply lines through a 
ntr oiler (starter) which controls and protects 
3 motor. 

In this chapter we shall describe the basic 
sration of motors, their construction, appli- 
tion, and the control devices associated with 



DC MOTORS 

There is very little difference in basic con- 
uction between a d.Co motor and a doC generator 
r, 4-1). A generator is rotated by a prime 
>ver to convert mechanical energy to electrical 
*rgy, whereas a motor is connected to a source 
electrical power and con verts electrical energy 
mechanical energy. A d.c. generator may 
made to function as a motor if you apply 
suitable source of direct voltage across the 
:mal output electrical terminals as described 
no-break power supplies. 

The operation of a d.c. motor depends on 
principle that a current-carrying conductor 
ced within, and at right angles to, a magnetic 
Id tends to move at right angles to the direction 
iie field, as shown in figure 4-2. 

The magnetic field between the north and 
south poles of a magnet is shown in figure 
!A. The lines of force comprising the field 
end from the north pole to the south pole, 
yross section of a current-carrying conductor 
re) is shown in figure 4-2B. The plus sign 
bin the wire indicates that the electron flow 



is away from the observer. The flux loops 
counterclockwise around the wire, as shown. 
This follows the left-hand rule which states 
that if the conductor is grasped in the left 
hand with the thumb extended in the direction 
of the current flow, the fingers will curve around 
the conductor in the direction of the magnetic 
flux. 

If the conductor (carrying the electron flow 
away from the observer) is placed between 
the poles of the magnet, as in figure 4-2C, 
both fields will be distorted. Above the wire 
the field is weakened, and the conductor tends 
to move upward* The force exerted depends on 
the strength of the field between the poles 
and on the strength of the current flowing through 
the wire. 

If the current through the conductor is re- 
versed, as in figure 4-2D, the direction of the 
flux loops around the wire is reversed. The 
field below the conductor is now weakened, and 
the conductor tends to move downward. This 
force, which acts on the conductor under these 
conditions, is directly proportional to the strength 
of the magnetic field, the magnitude of the current, 
and the length of the conductor. 

Since a motor is a rotating machine, the force 
exerted on the armature conductor is expressed 
in torque as measured at the motor shaft. The 
torque for a given motor is therefore directly 
proportional to the armature current and the 
strength of the magnetic field. 

The various types of d.c. motors (fig. 4-3) 
are identified by the way the field coils are 
connected. Each type has characteristics that 
are advantageous under given load conditions. 

SHUNT MOTORS 

In figure 4-3A the field coils are connected 
in parallel with the armature circuit. This type 



SHIPBOARD ELECTRICAL SYSTEMS 



END BELL 



AIR OUTLET 
COMMUTATOR 



ARMATURE 
COIL 



TERMINAL 
BOX 




BEARING OUTER 

' CAP 



BRUSH STUD 
INSULATOR 

BRUSH STUD 



MAIN FIELD COIL 
ARMATURE CORE 



MAIN POLE PIECE 
FRAME 

BAFFLE PLATE 



GREASE SLINGER 



END BELL 



Figure 4rl. D.c. motor. 



motor, with constant potential (voltage) applied, 
develops variable torque at an essentially constant 
speed, even under changing load conditions. Such 
* fOUnd in ^achine shop motors and 



73.161 



SERIES MOTORS 

In figure 4-3B the field coils are connected 
in series with the armature circuit. This type 
motor, with constant potential applied, develop 
variable torque, but its speed varies wideli 



54 



Chapter 4 MOTORS AND CONTROLLERS 




FIELD FLUX 
A 





FLUX AROUND 
CONDUCTORS 
B 




MOTION UP 
C 



MOTION DOWN 
D 



236,359 

.gure 4-2. Force acting on a current-carrying 
conductor in a magnetic field. 



ider changing load conditions. That is, the 
>eed is low under heavy loads but becomes 
icessively high under light loads. Series motors 
e commonly used to drive electric cranes, 
dsts, winches, and certain types of vehicles 
>r example, electric trucks). Series motors 
e used extensively to start internal combustion 
igines. CAUTION: A series motor that is run 
.thout load will destroy itself by overspeed. 

IMPOUND MOTORS 

Figure 4-3C shows a compound motor a 
mpromise between shunt and series motors, 
le set of field coils is connected in parallel 
th the armature circuit, and the other set 

field coils is connected in series with the 
mature circuit. A compound motor develops 
. increased starting torque over that of the 
.unt motor and has less variation in speed 
an the series motor. Shunt, series, and com- 
und motors are all d.c* motors designed 

operate from constant-potential, variable- 
rrent d.c. sources. 

'ABILIZED SHUNT MOTORS 

Figure 4-3D shows a stabilized shunt motor a 
jht series winding in addition to the shunt 



SHUNT 
FIELD 



SERIES FIELD 





ARMATURE 



ARMATURE 



SHUNT 
A 



SERIES 




ARMATURE 




SERIES 
FIELD 



ARMATURE 



COMPOUND 
C 



STABILIZED SHUNT 
D 



236.356 

Figure 4-3. Schematic diagrams of four types 
of d.c. motors. 



field. The action is similar to ordinary shunt 
motors except stabilized shunt motor shave better 
torque characteristics with less field iron and 
therefore are lighter in weight. 



AC MOTORS 

The majority of Navy ships utilize a.c, motors 
for electromechanical energy for several reasons. 
As previously discussed, most ship's service 
generators produce alternating current, thus 
making it readily available. Also ac. motors 
are generally less expensive than d.c, motors. 
Most types of a.c. motors do not employ brushes 
and commutators, thereby eliminating dangerous 
sparking as well as the many problems of main- 
tenance and wear. 



55 






A.c. motors are designed for use with poly- 
phase or single-phase power systems and come 
in many different sizes, shapes, and ratings. We 
cannot possibly cover all a.c. motors in this 
chapter. Consequently, we shall deal with the 
operating principles and applications of the four 
most common types found aboard ship: the 
polyphase induction motor and the single phase 
motors which include the split-phase motor, 
the capacitor motor, and the universal motor* 

So that you will better under stand the operating 
principles of polyphase induction motors, let us 
briefly discuss the a.c. theory. Referring to 
figure 4-4 you will see the manner in which a 
rotating field is produced by stationary coils, 
or windings, when they are supplied by a 3-phase 
power source. For purposes of explanation, rota- 
tion of the field is developed in figure 4-4 by 
"stopping" it at six selected positions, or instants. 
These instants are marked off at 60 intervals 
on the sine waves, representing currents in the 
three phases A, B, and C. 

At instant (1) the current in phase B is 
maximum positive. (Assume plus 10 amperes 
in this example). Current is considered to be 
positive when it is flowing out from a motor 
terminal. At the same time (instant 1) current 
flows into the A and C terminals at half value 
(minus 5 amperes each in this case). These 
currents combine at the neutral (common con- 
nection) to supply plus 10 amperes out through 
the B phase. 

The resulting field at instant (1) is established 
downward and to the right, as shown by the arrow 
NS. The major portion of this field is produced 
by phase B (full strength at this time) and is 
aided by the adjacent phases A and C (half 
strength). The weaker portions of the field 
are indicated by the letters "n" and "s." 
The field is two-pole extending across the space 
that would normally contain the rotor. 

At instant (2) the current in phase B is 
reduced to half value (plus 5 amperes in this 
example). The current in phase C has reversed 
its flow from minus 5 amperes to plus 5 amperes 
and the current in phase A has increased from 
minus 5 to minus 10 amperes. 

The resulting field at instant (2) is now 
established upward and to the right, as shown 
by the arrow NS. The major portion of the field 
is produced by phase A (full strength), and the 



weaker portions are produced by phases B ,ind 
C (half strength). 

At instant (3) the current in phase C is plus 
10 amperes and the field extends vertically 
upward; at instant (4) the current in phase B 
becomes minus 10 amperes, and the field extends 
upward and to the left; at instant (5) the current 
in phase A becomes plus 10 amperes, and the 
field extends downward and to the left; at instant 

(6) the current in phase C is minus 10 amperes, 
and the field extends vertically downward. Instant 

(7) (not shown) corresponds to instant (1) when 
the field again extends downward and to the right, 

Thus, a full rotation of the two-pole field 
has been accomplished through one full cycle oi 
360 electrical degrees of the 3-phase currents 
flowing in the windings. 

POLYPHASE INDUCTION 
MOTORS 

The driving torque of both d.c. and a.c, 
motors is derived from the reaction of current- 
carrying conductors in a magnetic field. You 
will recall that in the d.c, motor the magnetic 
field is stationary and the armature, with its 
current-carrying conductors, rotates. The cur- 
rent is supplied to the armature through a 
commutator and brushes. 

In induction motors (fig. 4-5) the rotor cur- 
rents are supplied by electromagnetic induction, 
The stator windings (coils) receive the 3-phase 
power and produce the previously mentioned ro- 
tating magnetic field. The magnetic field rotates 
continuously at constant speed (synchronous) 
regardless of the load on the motor. The rotor 
is not connected electrically to the power supply, 
The induction motor derives its name from the 
fact that electromagnetic induction takes place 
between the stator and the rotor under operating 
conditions* The magnetic revolving field pro- 
duced by the stator cuts across the rotor con- 
ductors, thereby inducing a voltage in the 
conductors. The induced voltage causes rotor 
current to flow. Hence, motor torque is developed 
by the interaction of the rotor's magnetic field 
and the stator 's revolving magnetic field. 

Most larger a.c. motors which are used on 
naval ships are polyphase (3-phase) induction 
motors. 

Figure 4-6 shows the rotor and stator of a 
typical polyphase induction motor. 



56 




<N 

si 



<D 
CO 



<D 

S3 
bO 



s 



CD 

a 



4. 

0) 



57 



BALL BEARING 



BEARING 
OUTER CAP 



-AIR CONE 



BALANCING DISK 



LOADING 
SPRING 



END BELL 



BEARING INNER 
CAP 



DRIPROOF COVER 




AIR OUTLET 



TERMINAL BOX 
LEAD CLAMP 

TERMINAL BOX 



END BELL 



INLET 



STATOR COIL 

ROTOR 
FAN BLADE 



STATOR CORE 
FRAME 



ROTOR CORE 
BEARING INNER CAP 

BALL BEARING 



GREASE SLINGER 



BALANCING DISK 



BEARING 
OUTER CUP 



Figure 4-5 3-phase induction motor 



73.161 



SINGLE-PHASE 
MOTORS 

Single-phase motors, as their name implies, 
operate on a single-phase power supply. These 
motors are used extensively in fractional horse- 
power sizes in commercial and domestic appli- 
cations. The advantages of using single-phase 



motors in small sizes are that they are less 
expensive to manufacture than other types, and 
they eliminate the need for 3-phase a.c* lines, 
Single-phase motors are used in interior com- 
munications equipment, fans, refrigerators, port- 
able drills, grinders, and so forth. 

A single-phase induction motor with only one 
stator winding and a cage rotor is like the 



58 




A. ROTOR 




B. STATOR 



73.147-77.77 

Figure 4-6. Typical polyphase induction motor 
(stator and rotor). 



3-phase induction motor with a cage rotor except 
that the single-phase motor has no revolving 
magnetic field at start, hence, no starting torque. 
However, if the rotor is brought up to speed 
by external means, the induced currents in the 
rotor will cooperate with the stator currents 
to produce a revolving field. This causes the 
rotor to continue to run in the direction in 
which it was started. 

Several methods are used to provide the 
single-phase motor with starting torque. These 
methods identify the motor as split phase, capaci- 
tor, etc. Another single-phase motor, which 
WQ shall discuss later, is the a.c. series motor 
(universal). 

SPLIT- PHASE MOTOR 

The split-phase motor (fig, 4-7A) has a 
stator composed of slotted laminations which 



contain an auxiliary (starting) winding and a 
running (main) winding. The axes of these two 
windings are displaced by an angle of 90 elec- 
trical degrees. The starting winding has fewer 
turns and smaller wire than the running winding; 
hence, the starting winding has higher resistance 
and less reactance. The main winding occupies 
the lower half of .the slots, and the starting 
winding occupies the upper half. The two windings 
are connected in parallel across the single- 
phase line which supplies the motor. The motor 
derives its name from the action of the stator 
during the starting period. The single-phase 
stator is split into two windings (phases), which 
are displaced in space by 90, and which contain 
currents displaced in time phase by an angle 
of approximately 15 (fig. 4-7B). In the starting 
winding, current I s lags the line voltage by 
approximately 30 and is less than the current 
in the main winding because of the higher im- 
pedance (AC resistance) of the starting winding. 
In the main winding, the current, 1^ lags the 
applied voltage by approximately 45. The total 
current, In ne , during the starting period is 
the vector sum of I s and I M . 

At start, these two windings produce a mag- 
netic revolving field which rotates around the 
stator air-gap at synchronous speed. As the 
rotating field moves around the air gap, it cuts 
across the rotor conductors and induces a voltage 
in them, which is maximum in the area of highest 
field intensity and, therefore, is in phase with 
the stator field. The rotor current lags the rotor 
voltage at start by an angle that approaches 
90 because of the high rotor reactance. The 
interaction of the rotor currents and the stator 
field causes the rotor to accelerate in the 
direction in which the stator field is rotating. 
During acceleration the rotor voltage, current, 
and reactance are reduced, and the rotor currents 
come closer to an inphase relation with the 
stator field. 



When the rotor has come up to approximately 
75 percent of synchronous speed, a centrifugally 
operated switch (fig. 4-8) disconnects the starting 
winding from the line supply, and the motor con- 
tinues to run on the main winding alone. There- 
after, the rotating field is maintained by the 
interaction of the rotor magnetomotive force and 
the stator magnetomotive force. These two mmf's 
are pictured as the vertical and horizontal 
vectors respectively in the schematic diagram 
in figure 4-7C. 



59 



SHIPBOARD ELECTRICAL SYSTEMS 



"LINE 



1 


CENTRIFUGAL 
SWITCH 


f 






SINGLE-PHASE 






SO 


JRCE 


-J 




MAIN 




i 


\ 


WINDING 


noorv I 


STARTING 




WINDING 




LINE 



CIRCUIT 



VECTORS FOR 
STARTING 



ROTOR MMF 




STATOR MMF 



RUNNING 
ANALYSIS 



Figure 4-7. Split-phase motor. 



236.323 



The stator field is assumed to be rotating 
at synchronous speed in a clockwise direction, 
and the stator currents correspond to the instant 
that the field is horizontal and extending from 
left to right across the airgap. The left-hand 
rule for magnetic polarity of the stator indicates 
that the stator currents will produce an N pole 
on the left side of the stator and an S pole on 
the right side. The motor indicated in figure 
4-7C is wpund for two poles. 



CAPACITOR MOTOR 

The capacitor motor is single-phase and has 
a capacitor in series with the starting winding. 
An external view is shown in figure 4-9 with 



the capacitor located on top of the motor. The 
capacitor produces a greater phase displacement 
of currents in the starting and running windings 
than is produced in the split-phase motor. The 
starting winding in the capacitor motor is made 
of many more turns of larger wire than that 
in the split-phase motor and is connected in 
series with the capacitor. The starting winding 
current is displaced approximately 90 from 
the running winding current. Since the axes 
of the two windings are also displaced by an 
angle of 90, a higher starting torque is produced 
than that in the split-phase motor. The starting 
torque of the capacitor motor may be as much 
as 350 percent of the full-load torque. 

If the starting winding is cut out after the 
motor has increased in speed, the motor is 



60 



Chapter 4 MOTORS AND CONTROLLERS 



RUNM1NG OR 
MAW WINDING 




END BELL 



END BELL 



CENTRIFUGAL SWITCH 



STATOR 



Figure 4-8. Exploded view of a split-phase motor. 



27.317 




Figure 4-9. Capacitor motor. 



236.324 



called a CAPACITOR-START MOTOR. If the 
starting winding and capacitor are designed 
to be left continuously in the circuit, the motor 
is called a CAPACITOR-RUN MOTOR. Electro- 
lytic capacitors for capacitor-start motors vary 
in size from approximately 80 microfarads for 
1/8-horsepower motors to 400 microfarads for 
1-horsepower motors. Capacitor motors of both 
types are made in sizes ranging from small 
fractional horsepower motor sup to approximately 
10 horsepower. They are used to drive grinders, 
drill presses, refrigerator compressors, and 
other loads which require relatively high starting 
torque. The direction of rotation of the capacitor 
motor may be reversed by interchanging the 
starting and winding leads. 



UNIVERSAL MOTOR 

A universal motor (fig. 4-10) can be operated 
on either d.c. or single-phase a.c. Aboard Navy 
ships, they are used extensively for portable 
tools. The motor is constructed with a main 
field connected in series with an armature. The 
armature is similar in construction to any d.c. 
motor. When electric power is applied, the mag- 
netic force created by the fields will react with 
the magnetic field in the armature and cause 
rotation* 



SHIPBOARD ELECTRICAL SYSTEMS 




27*357 
and uni- 



Figure 4-10. Portable electric drill 
versal motor parts. 

CONTROLLERS 



A controller is a device, or group of devices, 
which connects or disconnects the power supply 
to a motor. Most controllers also provide over- 
load protection (overcurrent) for the motor. Some 
controllers are designed to reverse and select 
speeds on certain motors. Although controllers 
are designed in many different ways, we shall 
discuss only the basic fundamentals of controllers. 
You will find more detailed information in NAV- 
SHIPS Technical Manual, Chapter 9630, EM 3& 2, 
NAVEDTRA 10546-D, and the manufacturer's 
technical manual. 

Controllers on naval vessels are either manual 
or magnetic for both a.c. or d.c. 

A MANUAL or nonautomatic controller (fig. 
4-11) is operated by hand directly through a 
mechanical system . The operator closes and opens 
the contacts that normally energize and de- 
energize the connected load. In a MAGNETIC 




27,358 



Figure 4-11. Manual controller. 



controller these contacts are closed and opened 
by electromechanical devices that are operated 
by local or remote master switches. Magnetic 
controllers may be semiautomatic or automatic, 

DC CONTROLLERS 

The starting of most d.c. motors, with the 
exception of fractional horsepower sizes, requires 



Chapter 4 MOTORS AND CONTROLLERS 



i temporary insertion of resistance in series 
yith the armature circuit to limit the high 
n-rush current at standstill. Because of this 
consideration, the starting resistance cannot be 
jafely removed from the line until the motor 
ias accelerated in speed and the counter electro- 
notive force is of sufficient strength to limit 
he current to a safe value. This is normally 
tccomplished with a d.c. controller (fig. 4-12). 
The connections for a motor controller with 
me stage of acceleration is shown in figure 



4-13. When the START button is pressed, the 
path for current is from line terminal L2 through 
the control fuse, STOP button, the closed START 
button, and the line contactor coil LC to line 
terminal LI. Current flowing through the con- 
tactor coil (LC) causes the contactor to pull in 
and close the line contacts, LCI, LC2, LC3, and 
LC4. 

When contacts LCI and LC2 close, motor- 
starting current flows through the series field 
SE, the motor armature A, the series relay 



STARTING 
RESISTORS 



MAIN 
CONTACTOR 




ACCELERATION 
CONTACTOR 



OVERLOAD 
DEVICE 



27.318X 



Figure 4-12.- A typical d.c. controller. 



SHIPBOARD ELECTRICAL SYSTEMS 



L2 rt 




LC4 



Figure 4-13. D.c. controller with one stage of acceleration. 



77.140 



coil SR, the starting resistor R, and the overload 
relay coil OL. At the same time, the shunt 
field winding SH, is connected across the line 
and establishes normal shunt field strength. Con- 
tacts LC3 close and prepare the circuit for the 
accelerating contactor coil AC. Contacts LC4 
close the holding circuit for the line contactor 
coil LC. The START button can now be released. 

The motor armature current flowing through 
the series relay coil causes its contactor to 
pull in, thereby opening the normally closed 
contacts SR. As the motor speed picks up, the 
armature current drawn from the line decreases. 
At approximately 110 percent of normal running 
current, the series relay current is not enough 
to hold its contactor in; therefore, it drops 
out and closes its contacts SR. These contacts 
are in series with the accelerating relay coil 
AC, causing it to pick up its contactor, closing 
contacts ACI and AC2. 

Auxiliary contacts ACI on the accelerating 
relay keep the circuit to the relay coil closed 
while the main contacts AC 2 shunt out the starting 
resistor and the series relay coil. The motor is 
then connected directly across the line, and the 
connection will be maintained until the STOP 
button is pressed. 



If the motor becomes overloaded, the excessive 
current through the overload coil (OL at the top 
right of fig. 4-13) will open the overload contacts 
(at the bottom of fig. 4-13) to disconnect the 
motor from the line. 

If the main contactor drops out because 
of an excessive drop in line voltage or because 
of a power failure, the motor will remain dis- 
connected from the line until an operator restarts 
it with the START pushbutton. 

AC CONTROLLERS 

Ac motors usually draw less power on starting, 
therefore starting resistance is not normally 
required on a.c. controllers. Most a.c. con- 
trollers are coupled to their power supply by 
across-line controllers. A typical 3-phase 
across-line controller consists of a 3-pole main- 
line contactor, two overload relays, mounting 
panel, an enclosure with mechanical overload- 
relay reset mechanism, and a master switch 
(start- stop pushbutton), as shown in figure 4-14. 
A schematic diagram of 3-phase a.c. across- 
the-line magnetic controller with overload and 
low voltage protection is shown in figure 4-15, 

The motor is started by pushing the START 
button (fig. 4-15). This action completes the 
circuit from L3 through the control fuse, STOP 



64 



Chapter 4 MOTORS AND CONTROLLERS 




Figure 4-14. Across-the-line, 3-phase, a.c. controller, pictoral view. 



27.319X 




TO 3 PH. 
A.C.SUPPLY 



10 A 

CONTROL 
FUSE 



MOMENTARY 
CONTACT 

PUSHBUTTONS 



77.132 

rigure4-15. Ac. controller with low voltage and 
overload protection, schematic diagram* 



button, START button, the overload relay con- 
tacts OL, and the contactor coil M to LI. 
When the coil is energized, it closes line con- 
tacts Ml, M2, and M3, which connect the full- line 
voltage to the motor 9 The line contactor auxiliary 
contact MA also closes and completes a holding 
circuit to maintain the M coil energized after 
the START pushbutton has been released. 

The motor will continue to run until the 
contactor coil is deenergized by the STOP push- 
button, failure of the line voltage, or tripping 
of the overload relay OL. Some larger a.c 
motors might require a limiting (controller) 
device in starting, which may be of the auto- 
transformer type, the reactor controller type, 
or the primary resistor type, 

Controllers are grouped under one of the 
following protective features: Low voltage pro- 
tection, low voltage release, or low voltage 
release effecto 



SHIPBOARD ELECTRICAL SYSTEMS 



Low- Voltage 
Protection (LVP) 

A low- voltage protection magnetic controller, 
upon loss or excessive reduction of supply voltage, 
disconnects the motor from the power supply 
and keeps it disconnected until the supply voltage 
returns to normal and the operator restarts the 
motor. This protects the power supply from over- 
load upon restoration of power. LVP is desirable 
for auxiliaries which are not so essential that 
they must be restarted immediately. 

Low-Voltage 
Release (LVR) 

A low-voltage release magnetic controller, 
upon reduction or loss of supply voltage, dis- 
connects the motor from the power supply, 
keeps it disconnected until the supply voltage 
returns to normal, and then automatically re starts 
the motor. Controllers with this feature are 
used only for auxiliaries which must be restarted 
immediately upon restoration of power. 

Low-Voltage 

Release Effect (LVRE) 

A low-voltage release effect controller pro- 
vides the same effect in manual controllers 
as is obtainable in a low-voltage release type' 
magnetic controller. That is, it will restart 
automatically upon restoration of power. 



A 
B 
C 



AND SYMBOL 



A 
B 
C 




OR SYMBOL 





J 1 
B l 1 




F 




1 1 
c l 1 





H'h 



OR CIRCUIT 



77.35 



Figure 4-17. OR symbol and circuit. 



LOGIC CONTROLLERS 

All control circuits employ logic. The basic 
electrical controls use electrical and mechanics! 
devices to perform their logic. In figure 4-16A 
you can see that contacts a, b, and c mug 
ALL be closed to energize the relay, there]]] 
creating an output. The same transistor circui: 
switch (electronic switch) can be used and is 
represented by the logic symbol (AND) show 
in figure 4-16B. 

Another electrical circuit is shown in figure 
4-17A. As you can see, EITHER a or b contact 
can be closed thus energizing the relay anc 
obtaining an output. The comparable logic symbol 
(OR) is shown in figure 4-1 7B. 

Using the characteristics of the AND and OR 
logic symbols we shall discuss how they cat 
be used in a logic controller. 



B c 



HHH 



"-2 



OUTPUT 
AND CIRCUIT 

77.356 
Figure 4~16 AND symbol and circuit. 



2ND- 
3RD' 



AND 



LOGIC 
SYMBOL 
AMPLIFIER 



ON A DECK 

ACCESS 

DOOR SHUT 




77.370 



Figure 4-18. Basic logic circuit. 



Chapter 4 MOTORS AND CONTROLLERS 



One common application of logic control that 
is being incorporated on newer ships is the 
elevator system. Since this system is large 
with many symbols, we shall show only a small 
portion. 

Let us assume that the elevator platform is 
on the third deck and that you require it on 
the main deck. Refer to figure 4-18* Three 
conditions must be met before the elevator can 
be safely moved. These conditions are detected 
by electronic sensors usually associated with 



the driven component. One of the conditions is 
that the platform must be on EITHER the second 
or third deck (on a certain deck as opposed to 
somewhere in between). If this condition is 
sensed, the OR symbol will have an input, and 
since only one input is needed, the OR symbol will 
also have an output. 

The other conditions to be met are that the 
locking devices must be engaged and the access 
doors must be shut. If the sensors are ener- 
gized for these two Conditions, the AND symbol 




Figure 4-19. A static logic panel for a cargo elevator. 



77.290 



will have the three inputs necessary to produce 
an output. This output will then set up a starting 
circuit allowing the motor to be started at your 
final command. 

The advantages of these electronic switches 
over mechanical switches are low power con- 
sumption, no moving parts, less maintenance, 



quicker response, and less space requirement 
A typical static logic panel found aboard sh 
is shown in figure 4-19 a 

Although there are logic symbols other tin 
AND and OR, they all incorporate solid sta 
devices. More information can be found in Ele< 
trician's Mate 3 & 2, NAVEDTRA 10546-D. 



68 



CHAPTER 5 

SHIPBOARD LIGHTING 



The lighting aboard ship is one of the most 
important systems and, many times, one of the 
most neglected. Several factors contribute to 
this seeming paradox maintenance in progress 
on other systems, constant illumination in some 
spaces, jury rigs, unauthorized changes, etc 

Because of the continuous and unusual demands 
on shipboard lighting systems, a vigorous program 
of preventive and corrective maintenance must 
be established and maintained. The most im- 
portant feature of such a program is the protection 
of personnel and equipment against electrical 
hazards. We cannot stress enough: ALL SAFETY 
PRECAUTIONS MUST BE CAREFULLY OB- 
SERVED. 

We shall discuss light sources that produce 
general ambient illumination, as well as special 
lighting applications. You will find more in- 
formation on lighting systems and safety pre- 
cautions in NAVSHIPS Technical Manual, chapter 
9600; Electric Shock Its Cause and Its Pre- 
vention, NAVSHIPS 250-660-42; and Lighting 
on Naval Ships, NAVSEA 0964-000-2000. 



LIGHT SOURCES 

The primary purpose of a light source is 
simply to produce light. The most common sources 
of electric light used aboard naval ships are 
the (1) incandescent, (2) fluorescent, and (3) glow 
lamps. There is a complete listing of the lamps 
used by the Navy in federal item '.dentification 
number sequence in the Illustrated Shipboard 
Shopping Guide (ISSG) FSC 6240. This listing is 
carried aboard all ships and includes the elec- 
trical characteristics, physical dimensions, and 
an outlirte of each Navy type lamp. 

INCANDESCENT LAMPS 

Incandescent lamps produce light by means 
of a tungsten or carbon filament which is heated 
to incandescense by an electric current. Oxidation 



with its attendant failure is prevented by sur- 
rounding the filament with an inert gas or by 
operating it in avacuuiru Most incandescent lamps 
used for shipboard lighting are 115-120 volts, 
25-200 watt, inside frosted, rough service (RS) 
lamps. RS lamps (fig. 5-1) have specially con- 
structed filaments supported at several points 
to increase their ability to withstand shock. 
The frosting conceals the filament and diffuses 
the light emitted from the lamp. These lamps 
may be used with or without reflecting equipment. 

DESIGNATION 

Standard incandescent lamps are designated 
according to the (1) shape of bulb, (2) the finish 
of bulb, (3) the type of base, and (4) the size 
of the base. 



BASE 



BULB 
(ENVELOPE) 




STEM 



LEAD-IN WIRE 



SUPPORT 



FILAMENT 



12.359 
Figure 5-1. Components of an incandescent lamp. 



69 



SHIPBOARD ELECTRICAL SYSTEMS 



The shape of the bulb is identified by a 
corresponding letter designation, as illustrated 
in figure 5- 2 A. The designation letter is followed 
by a numeral (not shown) that denotes the diameter 
of the bulb in eighths of an inch. 

The designation of lamps according to the type 
of base is illustrated in figure 5-2B. The size 
of the base is indicated by name mogul, candela- 
bra, intermediate, etc. Each type of base is 
provided in different sizes. The types are also 
denoted by name bayonet, prefocus, bipost, etc. 

Most lamps aboard ship are of the frosted 
finish type to help eliminate the glare of the 
filament. 

CHARACTERISTICS 

The average life of standard lamps for general 
lighting service, when operated at rated voltage, 
is 750 hours for some sizes and 1000 hours for 
others. The light output, life, and electrical 
characteristics of a lamp are materially affected 
when it is operated at other than the design 
voltage. Operating a lamp at less than rated 
voltage will prolong the life of the lamp but 
will decrease the light output. Conversely, oper- 
ating a lamp at a higher than rated voltage will 
shorten the life but will increase the light output. 
Lamps should be operated as closely as possible 
to their rated voltage. 

FLUORESCENT LAMPS 

Fluorescent lamps are now used for the 
majority of lighting aboard naval ships. They 
consume less power with greater illumination and 
therefore are more efficient than incandescent 
lamps. 

Construction 

The fluorescent lamp is an electric discharge 
lamp that consists of an elongated tubular bulb 
with an oxide- coated filament sealed into each 
end to contain two electrodes. The bulb contains 
a drop of mercury and a small amount of argon 
gas. The inside surface of the bulb is coated 
with a fluorescent phosphor. The lamp produces 
invisible, shortwave (ultraviolet) radiation by 
discharging current through the mercury vapor 
in the bulb. The phosphor absorbs the invisible 
radiant energy and reradiates it over a band 
of wavelengths to which the eye is sensitive. 

The Navy has standardized on three lamp 
sizes: 8 watts, 15 watts, and 20 watts. The use 
of fluorescent lamps of more than 20 watts 
is limited to special installations. 



Operation 

Fluorescent lamps installed aboard ship art 
of the hot-cathode, preheat starting type. 1 
fluorescent lamp equipped with a glow-switc! 
starter is illustrated in figure 5-3. The glow 
starter is essentially a glow lamp containin| 
neon or argon gas and two metallic electrodes, 
One electrode has a fixed contact, and tta 
other electrode is a U-shaped, bimetal strip 
having a movable contact. These contacts art 
normally open. 

When the circuit switch is closed, theit 
is practically no voltage drop across the ballast, 
and the voltage across the starter (S) is suffi- 
cient to produce a glow around the bimetallic 
strip in the glow lamp. The heat from the glm 
causes the bimetal strip to distort and touch 
the fixed electrode. This action shorts out the 
glow discharge and the bimetal strip starts to 
cool as the starting circuit of the fluorescent 
lamp is completed. The starting current flows 
through the lamp filament in each end of the 
fluorescent tube, causing the mercury to vaporize, 
Current does not flow across the lamp between the 
electrodes at this time because the path is 
short circuited by the starter and because the 
gas in the bulb is nonconducting when the elec- 
trodes are cold. The preheating of the fluorescent 
tube continues until the bimetal strip in the starter 
cools sufficiently to open the starting circuit, 

When the starting circuit opens, the decrease 
of current in the ballast produces an induced 
voltage across the lamp electrodes. The mag- 
nitude of this voltage is sufficient to ionize the 
mercury vapor and start the lamp. The resulting 
glow discharge (arc) through the fluorescent 
lamp produces a large amount of ultraviolet 
radiation that impinges on the phosphor, causing 
it to fluoresce and emit a relatively bright 
light, During normal operation the voltage across 
the fluorescent lamp is not sufficient to produce 
a glow in the starter. Hence, the contacts remain 
open and the starter consumes no energy. 

Characteristics 

As temperature increases above normal, the 
efficiency of fluorescent lamps decreases slowly, 
and as the temperature decreases below normal, 
efficiency decreases very rapidly. Hence, the 
fluorescent lamp is not satisfactory for locations 
in which it will be subjected to wide variations 
in temperature. 



Chapter 5 SHIPBOARD LIGHTING 




CONE (C) 





GLOBULAR (G) 



ARBITRARY (A) 



PARABOLIC (PAR) 
ALUMINIZED 
REFLECTOR 







PEAR SHAPED (P) PEAR SHAPE WITH REFLECTOR (R) STRAIGHT SIDE (S) TUBULAR (T) 
STRAIGHT SIDE (PS) 

A - SHAPE OF BULBS 



SCREW BAYONET FLANGED BIPIN 

(SINGLE CONTACT) (SINGLE CONTACT) 



A (MINIATURE) 



SCREW 

C (INTERMEDIATE) 




D (ADMEDIUM) 





PREFOCUS 
(SINGLE CONTACT) SCREW SKIRTED 



BIPIN 
(T-6-F LAMP) 




BIPIN 
(T-I2-F LAMP) 



SCREW SCREW WITH BAYONET BAYONET INDEXING 

SHORT NUB (SINGLE CONTACT) (DOUBLE CONTACT) 




BAYONET PREFOCUSING COLLAR PREFOCUSING COLLAR BAYONET SKIRTED 

(DOUBLE CONTACT) (SINGLE CONTACT) (DOUBLE CONTACT) (DOUBLE CONTACT) 

B (CANDELABRA) 




SCREW ' *" BIPIN 

SCREW (THREE CONTACT) PREFOCUS (T-I7-F LAMP) 




BIPOST 
(T-20 LAMP) 



F( MOGUL) 



B - TYPE OF BASE 

Figure 5-2. Classification of lamps. 



12.79:80 



SHIPBOARD ELECTRICAL SYSTEMS 



GLOW 
LAMP 



GLOW 

SWITCH 

S 



CIRCUIT 
SWITCH 




27.360 

Figure 5-3. Glow-switch starter and fluorescent 
lamp. 




Fluorescent lamps should be operated at 
voltage within 10% of their rated voltage. If 
the lamps are operated at lower voltages, un- 
certain starting may result, and if operated at 
higher voltages, the ballast may overheat. Oper- 
ation of the lamps at either lower or higher 
voltages results in decreased lamp life. The 
performance of fluorescent lamps depends to a 
great extent on the characteristics of the ballast, 
which determines the power delivered to the 
lamp for a given line voltage. 

The failure of a hot-cathode fluorescent lamp 
usually results from loss of electron-emissive 
material from the electrodes. This loss proceeds 
gradually throughout the life of the lamp and is 
accelerated by frequent starting. Blackening of 
the ends of the bulb progresses gradually through- 
out the life of the lamp. 

GLOW LAMPS 

Glow lamps are electric-discharge light 
sources which are used as indicator or pilot 
lights on various instruments, fuseholders, and 
control panels (fig. 5-4). Since glow lamps have 
a relatively low light output, they are used to 
indicate the energizing of circuits or the operation 
of electrical equipment in remote locations, 
rather than for illumination. These lamps offer 
the advantages of small size, ruggedness, long 
life, low power consumption, and operation in 
standard lighting circuits. 



7.40 
Figure 5-4. Fuse holder with glow lamp. 



The glow lamp consists of two closely spac 
metallic electrodes sealed in a glass bulb t 
contains an inert gas. The color of the 11 
emitted by the lamp depends on the gas. N( 
gas produces an orange- red light, and arj 
gas produces a blue light. The lamp must 
operated in series with a cur rent- limiting dev 
to stabilize the discharge. The current-limit 
device consists of a high resistance that 
sometimes contained in the lamp base. 

The glow lamp produces light only when' 
voltage exceeds a certain striking voltage, 
the voltage is decreased below this value, 
glow suddenly vanishes. When the lamp is opera 
on alternating current, light is produced o: 
during a portion of each half-cycle and b 
electrodes are alternately surrounded with a glc 
When the lamp is operated on direct curre 
light is produced continuously, and only 1 
negative electrode is surrounded with a glow. T] 
characteristic makes it possible to use the gl 
lamp as an indicator of both alternating curn 
and direct current. 



LIGHTING FIXTURES 

A lighting fixture is a device that hous 
the lighting source (lamp). It acts to prov: 



72 



Chapter 5 SHIPBOARD LIGHTING 



satisfactory illumination while reducing glare 
and affording protection to the lamp from mechan- 
ical and battle damage. Lighting fixtures are 
manufactured for incandescent (fig. 5-5A and B) 
or fluorescent (fig. 5-5C and D). 

Permanent fixtures (incandescent or fluo- 
rescent) are permanently installed to provide 
general illumination and such detail illumination 
as may be required in specific locations. GEN- 
ERAL ILLUMINATION is based on the light 
intensity required for the performance of normal 
routine duties, DETAIL ILLUMINATION is pro- 
vided where the general illumination is inadequate 
for the performance of specific tasks. Sources 



include berth fixtures, desk lamps, and plotting 
lamps* 

Portable fixtures are provided for lighting 
applications that cannot be served by permanently 
installed fixtures. These units are energized by 
means of portable cables that are plugged into 
outlets in the ship's service wiring system and 
include bedside lights, desk lights, floodlights 
and extension lights. 

TRANSFORMERS 

An understanding of transformers will help 
you follow the discussion on lighting systems. 





A INCANDESCENT OVERHEAD 
FIXTURE 



B INCANDESCENT 
BULKHEAD FIXTURE 




C FLUORESCENT OVERHEAD 
FIXTURE 



D FLUORESCENT 
DESK FIXTURE 



Figure 5-5. Lighting fixtures. 



77.38 



SHIPBOARD ELECTRICAL SYSTEMS 



Basically, transformers work on the same prin- 
ciples as the a.c induction motor described in 
chapter 4. That is, the primary winding (450 
VAC) receives power from the ship's service 
supply. The secondary winding (120 VAC) pro- 
duces a voltage due to the expanding and collaps- 
ing magnetic field of the primary. This induced 
voltage in the secondary is lower than the primary 
due to the winding turns ratio. This type trans- 
former is called a step-down transformer because 
of the lower voltage in the secondary. Similar to 
the a.c. induction motor, there are no electrical 
connections between the primary and secondary 
windings. 



LIGHTING SYSTEMS 

The lighting distribution system in naval 
vessels is designed for satisfactory illumination, 
optimum operational economy, maximum con- 
tinuity of service, and minimum vulnerability to 
mechanical and battle damage. Most ships have 
two sources of power supply for lighting fixtures. 
Normal supply is from the ship's service bus. 
A designated number of fixtures can also be 
supplied from the emergency distribution system. 
Additionally, there is a third lighting system 
that consists of battery-powered, relay-operated, 
hand lanterns. 

The first two systems consist of feeders from 
the ship's service or emergency power switch- 
boards, switchgear groups, or load centers to 
distribution panels or feeder distribution fuse 
boxes, located at central distribution points 
from which power is distributed .to the local 
lighting circuits. 

The ac. ship's service power feeders are 
normally 450-volt, 3-phase, 60-hertz circuits. 
The lighting supply circuits are 450 -volt, 3-phase, 
60-hertz, 3-wire circuits supplied from the power 
distribution system to 450/120-volt transformer 
banks. 

Three small transformers are used instead 
of one large transformer because the loss of a 
single composite unit would result in a total 
loss of power. By using three separate trans- 
formers, reliability is increased* In the event of 
an enemy hit or failure of one of the bank of 
three single-phase transformers (fig. 5-6), the 
remaining two will still carry approximately 
58 percent of the initial bank capacity. The line 




236.3 

Figure 5-6. Single-phase transformer. 



current must be sufficiently reduced to sts 
within the limits of the rated current of tt 
two remaining transformers. 

A typical vital lighting load has access 1 
two switchboards (fig. 5-7). Selection of eithe 
of these sources is automatic through an auto 
matic bus transfer (ABT) switch. Additionally 
the emergency switchboard has three powe 
supplies that are independent of each othei 
As a result of this arrangement, the vital lightin 
load can be automatically supplied from severs 
primary sources. 

The system ;3hown in figure 5-7 operates a 
follows. If an undervoltage condition develop 
on switchboard 2SA, which is the normal suppl; 
for ABT switch #1, the ABT switch will transfe: 
the lighting load center panel to the emergenc; 
lighting load center panel whose power sourc< 
is emergency switchboard 2E. 

Emergency switchboard 2E is energized eithe] 
from its normal or alternate ship's service 
supply feeders, or from the local emergencj 



Chapter 5 SHIPBOARD LIGHTING 



SSSWB 2SB 



450/120 X 

LIGHTING 

LOAD 
CENTER 

PANEL 



SS SWBD 2SA 



SSSWBO 1SB 



EMERGENCY c ^ ^ 
LIGHTING 4 ^0/J20 

LOAD 
CENTER 




VL 



BUS TIE 



EMERGENCY 

SWBD 

2E 



SSSWBO ISA 



450/1 2O 

HH 



EMERGENCY 

SWBO 

IE 




EMERGENCY 

GENERATOR 

2E 



EMERGENCY 

GENERATOR 

IE 



Figure 5-7. Typical lighting distribution system. 



77.48(770) 



generator. Transfer between these supplies is 
automatic by three electrically operated circuit 
breakers. The circuit breakers are electrically 
and mechanically interlocked to prevent closing 
of more than one breaker at a time. Normally, 
the emergency switchboard is energized from one 
of the two ship's service supplies. If voltage on 
the normal ship's service supply bus drops to 
300 volts, or below, the load automatically 
transfers to the alternate supply if 400 volts 
or above is available at that source. (If 400 
volts or above is restored to the normal supply, 
the load will automatically retransfer to the 
normal supply.) If both ship's service supplies 
fail completely or if their voltage drops to 300 
volts, the transfer system will operate auto- 
matically to start the emergency generator and 
connect it to the emergency switchboard. 



DARKENED SHIP 
EQUIPMENT 

Darkened ship is a security condition designed 
to prevent the exposure of light, which could 
reveal the location of the vessel. Darkened-ship 
condition is achieved by means of (1) light traps 
that prevent the escape of light from illuminated 
spaces, or (2) door switches that automatically 
disconnect the lights when the doors are opened. 

A light trap is an arrangement of screens 
placed inside access doors or hatches to prevent 
the escape of direct or reflected light from 
within (fig. 5-8). The inside surfaces of the 
screens are painted flat black so that they will 
reflect a minimum of light falling on them. 
Light traps that are used to prevent the escape 



75 



SHIPBOARD ELECTRICAL SYSTEMS 




P PAINT BLACK 
TO HERE 



Figure 5-8. Light trap. 



77.46 



of white light should have at least two black, 
light-absorbing surfaces interposed between the 
light source and the outboard openings. Light 
traps are preferred to door switches in locations 
where (1) exit and entrance are frequent; (2) 
interruption of light would cause work stoppage 
in large areas; (3) light might be exposed from 
a series of hatches, one above the other on 
successive deck levels; and (4) where many 
small compartments and passages are joined 
by numerous inside and outside doors that would 
complicate a door- switch installation. 

A door switch is mounted on the break side 
of a door jamb (inside the compartment) and 
operated by a stud welded to the door. When 
the door is opened, the switch automatically 
opens at the same time. Door switches are 
connected in a variety of ways to suit the 
arrangement of the compartment concerned. 

All door switch installations are provided 
with lock-in devices or short-circuiting switches 
to change the settings of the door switches, as 
required from lighted ship to darkened ship, and 
vice versa. 

RED ILLUMINATION 

When a person leaves a well-lighted space and 
enters a dimly lighted space, his vision is im- 
paired until his eyes become accustomed to 



the dark. When he can again see, his eyes are 
said to be dark adapted. For personnel having 
battle stations or watch stations topside, this time 
interval could be detrimental to his ability to 
stand his watch. The primary purpose of red 
illumination is to provide low-level illumination 
access routes to dimly lighted areas with minimum 
interference to dark-adapted vision. 

Red illumination is accomplished by using 
standard red light fixtures or red filters over 
standard white lights. 

BLUE ILLUMINATION 

A unique problem arises in the illumination 
of spaces that contain radar system display 
consoles. Normal lighting (standard white light) 
excites the phosphor coating on the inside of the 
cathode ray tube (CRT). This results in a dimming 
of the target trace , thereby affecting the operator's 
ability to see the target. 

The conventional solution for years was to 
darken the room. This improved the CRT display 
but hindered other important ongoing operations 
in the room, such as reading charts and messages, 
plotting on status boards, and PMS requirements, 

A solution to the problem was found by using 
blue illumination. The basic principle of this 
lighting system is frequency sharing. A broad 
band of blue light is allocated for ambient 
illumination, and the remaining portion of the 
visible spectrum :.s used for CRT viewing. The 
system is referred to as Broad Band Blue (BBB) 
lighting. 

White light contains all the colors of the 
visible spectrum, therefore, any ambient illumi- 
nation has some white light. By using two filters 
we can almost eliminate the white light to the 
CRT. 

A blue filter is placed over the fluorescent 
fixtures (fig. 5-9) which allows only the desired 
wavelengths to pass, leaving enough ambient 
illumination but decreasing the white available to 
interfere with the CRT. 

A second filter, amber, which will not pass 
the wavelengths of the blue light but will allow 
the CRT signal to foe seen, is placed over the 
CRT. 

The combination of blue and amber filters 
provides improved scope visibility with an illumi- 
nated working environment. 



Chapter 5 SHIPBOARD LIGHTING 



BBB FIXTURE- 
WITH 

DAYLIGHT 
LAMPS 



CRT SIGNAL PASSED 
BY SCOPE 
AMBER FILTER 




BLUE FILTER 
(TUBULAR) 



BLUE LIGHT 

REJECTED 

BY SCOPE AMBER 



Figure 5-9. BBB lighting system. 



27.361 



SPECIAL LIGHTING 
APPLICATIONS 

Up to this point we have limited our discussion 
of shipboard lighting to general ambient illumi- 
nation. In the next portion of this chapter we shall 
describe different lights and fixtures not generally 
associated with compartment illumination. 



REPLENISHMENT-AT- 
SEA RED LIGHTING 

To enable extended periods of operations at 
sea, units of the fleet receive the logistic support 
they require by means of replenishment~at-sea 
(RAS) operations. 

In the past most RAS operations were conducted 
during daylight hours because of visibility con- 
siderations. With increased demands for night 
operations the need for night RAS became increas- 
ingly important. RAS lighting (fig. 5-10) permits 
night replenishment with minimum risk to the 
safety of both ships and personnel. 



Hull Contour Lights 

Hull contour lights (fig. 5-10) consist of 
three red 25-watt lights shown by the control 
(replenishment) ship during the approach and 
while the receiving ship is alongside. These 
lights are located at the fore and aft extremes 
of that portion of the side parallel with the keel. 



*&*, 



TRUCK LIGHT (DIMMED) % 
SHOWN ONLY DURING 1 
APPROACH OF 
RECEIVING SHIP 






f *", TASK LIGHTS 
, (SHOWN ONLY WHEN 
> REQUIRED BY RULES 
OF THE ROAD) 



WAKE LIGHT 

SHOWN ONLY DURING 

APPROACH OF 

RECEIVING SHIP 




Figure 5-10. RAS lighting. 



27.362 



SHIPBOARD ELECTRICAL SYSTEMS 



Obstruction Lights 

The obstruction lights indicate to the control 
hin items which may interfere with the cargo 
^ 'it approaches the receiving ship, such as 
de^k edges, missile launches, etc. Six one-cell, 
-ed-lens, pin-on-type flashlights (fig. 5-11A) or 
ix chemical lights (fig. 5-11B) are attached in 
a straight line to a 6-inch wide, 12-foot long 
of white canvas, which is placed along the 



deck edge or along other obstructions outb 
of the receiving ship. 

Station Marker 
Light Box 

A portable light box (fig. 5-12) is loot 
at the replenishment station of both the com 
and approach ships. It uses a code (table E 
to indicate the commodity toeing transfer: 




Figure 5-11. One-cell flashlight and chemical light (obstruction lights). 

Phone/Distance 
Line Marking 




The phone/distance line is hung between tt 
two ships to indicate the distance between their, 
and can be used to hold sound-powered telephone 
cable. A single chemical light is attached at ever) 
20-foot interval along the phone/ distance line, J 
cluster of three chemical lights is interspersed 
along the line at 60-, 100-, and 140 r foot intervals, 
(See figure 5-13.) 



Lights for Work Areas 

To minimize danger to personnel, red flood- 
lights provide illumination in working areas on 
deck, in holds, and in cargo loading areas, 
A typical configuration is shown in figure 5-14, 



VISUAL LANDING 
AIDS 



Figure 5-12. -Station marking light 



Visual landing aids (VLA) are lighting devices 
and fixtures installed aboard nonaviation type 



78 



Chapter 5 SHIPBOARD LIGHTING 



Table 5-1. Station marking light box code 



COMMODITY 
TRANSFERRED 



MISSILES 



AMMUNITION 



FUEL OIL 



DIESEL OIL 



NAVY 
DISTILLATE (ND) 



AVGAS 



JET FUEL 
(JP-5) 



WATER 



STORES 



PERSONNEL AND/ 
OR LIGHT FREIGHT 



FUEL OIL AND 
JP-5 



ND AND JP-5 



STATION 

MARKER 

LIGHT BOX 







27.368 

ships to aid helicopter pilots in all-weather 
and night operations. 

Primarily the VLA system consists of a 
Stabilized Glide Slope Indicator (SGSI). The SGSI 
projects a tri-colored beam of light (fig. 5-15) 
centered along a safe glide path to the ship. 



The upper sector of the light beam is green, 
the center portion (command path) is amber, 
and the lower section is red. In operation the 
helicopter pilot flies into (acquires) the beam 
and follows the command path to the ship. The 
glide slope indicator is mounted on a stabilized 
platform which compensates for the ship's roll 
and pitch to keep the projected glide path steady. 
Other fixtures (fig. 5-16) indicate to the 
pilot the deck edge, the line-up position, the 
touchdown point, and any unfavorable landing 
condition. Various flood lights ilium "nate struc- 
tures around the landing area for better depth 
perception. 

NAVIGATION AND 
SIGNAL LIGHTS 

Running, anchor, and signal lights include 
all external lights used for navigational and 
signaling purposes between ships to reduce the 
possibility of collision and to transmit intelli- 
gence. For design convenience, these lights 
are divided into three groups as follows: 

(1) Navigation Lights (as specified by the 
International Rules of the Road) : 
Masthead 

Minesweeping 

Range 

Side-port 

Side- starbo ar d 

Stern (white) 

Towing 

Not-under-command (breakdown) and 

man-overboard 
Ship's task 
Anchor-aft 
Anchor-forward 

(2) Signal Lights (Station or Operational): 
Aircraft warning 

Stern (blue) 
Wake 

Contour approach light (replenishment) 
Polarity signal 

Speed light (also used as aircraft warn- 
ing or replenishment red truck lights) 
Station keeping (mine sweeping) 
Identification light for submarines 
Station marking box (replenishment) 
Revolving beam ASW light 

(3) Signal Lights (Visual Communication): 
Blinker 

8-inch searchlight 
12-inch searchlight (all types) 
Infrared transmitters 
Multipurpose signal light 



SHIPBOARD ELECTRICAL SYSTEMS 



USE A CLUSTER OF THREE CHEMICAL LIGHTS AT THE 60, 100 AND !40 FOOT 
MARKERS. USE ONE LIGHT AT ALL OTHER MARKERS. 



NOTE: PIN-ON ONE-CELL RED FLASHLIGHTS MAY BE USED 
IN LIEU OF CHEMICAL LIGHTS. 



CONTROL SHIP 



MARLINE 
1- CLASHING 



RECEIVING SHIP 



i$S#*TYPICAL INSTALLATION 




Figure 5-13. Phone/distance line markings. 



RAS LOW LEVEL (RED) FLOODLIGHTS 
TO MARK AND LIGHT LANDING AREA 



RAS LOW LEVEL (RED) FLOODLIGHTS 
TO ILLUMINATE WORKING AREAS 



STATION MARKING BOX 
SYMBOL 285 




OBSTRUCTION LIGHTS FOR DECK EDGE 



OBSTRUCTION LIGHTS 
FOR VERTICAL OBSTRUCTIONS 



Figure 5-14. RAS work area lighting on receiving ships. 

80 



27.366 



Chapter 5 SHIPBOARD LIGHTING 



VERTICAL FIELD ANGLE 



ANGLE OF 
ELEVATION 




FLIGHT 
DECK 



GSI 

LIGHT 

SOURCE 



<L 



GREEN 




AMBER 



RED 



111.172 



Figure 5-15. -Glide slope indicator and light beam. 



Navigation Lights 



The number location, arc, and range of 
visibility of the navigation lights, which must 
S displayed from sunset to sunrise by *n 
ships in international waters, are established 
Sy tie International Regulations "*"***"* 
Collisions at Sea. Title tt, United States Code 
Section 1051-1094, is the statutory law that 



requires the Navy to comply with the Inter- 
national Rules of the Road, or as allowed by an 
exfstSg waiver to be issued covering the vessel 
being built. 

MASTHEAD LIGHTS. -The masthead light 
(white) is a 20-point (225<) Alight ; located oj .fee 
foremast or in the forward part of the ^vessel. 
It is a spraytight fixture provided with a ^50- 
watt, 2-fUament lamp and equipped with an 



SHIPBOARD ELECTRICAL SYSTEMS 




(RED OR WHITE; 
DECK SURFACE 
FLOODLIGHTS 



(WHITE) 
LINE UP LIGHTS 



Figure 5-16 Typical VL A installation with night deck and hangar on 0-1 level, dual landing approach, 

82 



Chapter 5 SHIPBOARD LIGHTING 



external shield to show an unbroken light over 
an arc of the horizon of 20 points that is, from 
dead ahead to 2 points abaft the beam on either 
side. 

MINESWEEPING. The minesweeping lights 
(green) are three 32-point (360) lights arranged 
in a triangle on the forward mast. These lights 
are burned when mines are present to warn 
other ships of danger 3000 feet astern and 1500 
feet on the sides. 

RANGE LIGHTS. The range light (white) 
is a 20 -point (225) light located on the mainmast 
or the fore part of the vessel and is a spray- 
tight fixture provided with a 50-watt, 2-filament 
lamp. The vertical distance of the range light 
must be at least 15 feet higher than the mast- 
head light, and the horizontal distance must be 
greater than the vertical distance of the masthead 
light. 

PORT AND STARBOARD SIDE LIGHTS. 
The port and starboard side lights are 10 -point 
(112 1/2) lights (fig. 5-17) located on the re- 
spective sides of the vessel, showing red to 
port and green to starboard. The fixtures are 
spraytight, each provided with a 100 -watt, 2- 
filament lamp and equipped with an external 
shield arranged to throw the light from dead 



ahead to 2 points abaft the beam on the respec- 
tive sides. 

STERN LIGHT. The stern light (white) is 
a 12-point (135) light located on the stern 
of the vessel. It is a watertight fixture pro- 
vided with a 50-watt, 2-filament lamp and equipped 
with an external shield to show an unbroken 
light over an arc of the horizon of 12 points 
of the compass that is, from dead astern to 
6 points on each side of the ship. 

TOWING LIGHTS. The towing lights (white) 
for ships not normally engaged in towing opera- 
tions are 20-point (225) lights similar to the 
previously described masthead and range lights. 
They are portable fixtures, each equipped with 
a type THOF-3 cable and plug connector for 
energizing the lights from the nearest lighting 
receptacle connector. When these lights are 
used, they are located vertically (6 feet apart) 
in the fore part of the vessel. These lights 
can be permanently installed on ships whose 
normal operations call for towing, e.g., fleet 
tugs, salvage vessels, etc. 

BREAKDOWN AND MAN-OVERBOARD 
LIGHTS. The breakdown and man-overboard 
lights (red) are 32-point (360) lights located 12 
feet apart (vertically) and mounted on brackets 



IDENTIFICATION 
PLATE 




DIAGONAL 
SCREEN BASE 

PLATE 



FORE AND AFT 
SCREEN 



77.41 



Figure 5-17. Side light. 
83 



SHIPBOARD ELECTRICAL SYSTEMS 



* A oft of and to starboard of the mast 
that extend aft of ana rmnsvisiwl 

or structure. This arrange' O f azimuth. 

a rotaS snapswitch (fitted with a crank 

the signal and anchor light supply 

JrfcSntrol panel. These lights are mounted and 

in conjunction with the snap's task 

lights. 

SHIP'S TASK LIGHT. -The ship's task light 
is an array consisting of three 32-point (360) 
ghte, stepped out 45* aft and to starboard of 
the mast, in a vertical line, one over the other, 
so that the upper and lower lights are the same 
distance from, and not less than 6 feet above or 
below, the middle light and are visible all around 
the horizon at a distance of at least 2 miles. 
The upper and lower lights of this array are 
red. The center light is clear white. 

The ship's task lights are connected to the 
Navigational Light Supply and Control Panel so 
that: 

(1) The two red lights will burn steadily 
to indicate that the ship is Not-Under- Command; 

or 

(2) The two red lights will flash (by rotating 
the switch (crank type) handle) to indicate that 
a rnan-overboard condition exists; or 

(3) The three lights will burn simultaneously 
to indicate that the ship is either launching or 
recovering aircraft or is engaged in replen- 
ishment-at-sea operations and, by the nature 
of her work, is unable to get out of the way of 
approaching vessels. The switch for this appli- 
cation is labeled c 'Ship's Task Lights." 

FORWARD AND AFTER ANCHOR LIGHTS. 
The forward and after anchor lights (white) 
are 32-point (360) lights. The forward anchor 
light is located near the bow of the vessel, and 
the after anchor light is at the top of the flag- 
staff. The fixtures are splashproof, each provided 
with a 50-watt, 1-filament lamp. The anchor 
lights are energized through individual on-off 
rotary snap switches on the signal and anchor 
light supply and control panel in the pilothouse. 

SUPPLY CONTROL AND TELLTALE 
PANEL. -The supply, control, and telltale panel 
for the running lights is a nonwatertight, sheet 
metal cabinet designed for bulkhead mounting; 

(fig. 5-18). B 




Figure 5-18. Supply, control, and telltale 

This panel is provided to aid a ship in ! 
her running lights in operation as prei 
by the rules for preventing collisions ; 
It is installed in or near the pilothouse ant 
an alarm whenever one of the running 
(masthead, stern, range, and side lights) 
or has had a failure of its primary filanii 
is operating on its secondary filament* 

A dimmer control panel is used to d 
running lights when directed. This panel pi- 
only one position for dimming. In the dim p< 
the visibility of the range, masthead, side 
and stern light is reduced to approximate!; 
yards. 

Signal Lights (Station 
or Operational) 

AIRCRAFT WARNING LIGHT. The at 
warning lights (red) are 32-point (360) 



84 



Chapter 5 SHIPBOARD LIGHTING 



(fig. 5-19A) installed at the truck of each mast 
that extends more than 25 feet above the highest 
point in the superstructure. Two aircraft warning 
lights are installed if the light cannot be placed 
so that it is visible from any location throughout 
360 of azimuth. However, a separate aircraft 
warning light is not required if a 32-point red 
light is installed at the truck of a mast for 
another purpose. The fixtures are spraytight 
and equipped with multiple sockets provided 
with 15-watt, 1-filament lamps (fig. 5-1 9 A). 
If a single lamp fails, all of the lamps in the 
cluster should be replaced. 



SPEED LIGHTS. The speed lights are combi- 
nation red (top) and white (bottom), 32-point 
(360) lights (fig. 5-19B). They are located at 
the truck (top) of the mainmast, except when 
the height of the foremast is such that it inter- 
feres with their visibility; in this case, they are 
located at the truck of the foremast. Two speed 
lights are installed if their light cannot be 
placed so that they are visible throughout 360 
of azimuth. 

Speed lights are provided to indicate (by means 
of a coded signal) the speed of the vessel to 
ships in formation. In other words, they indicate 
the order being transmitted over the engine order 
system. The white light indicates ahead speeds, 
and the red light indicates stopping and backing. 
The fixture is spraytight and equipped with a 
multiple socket (fig. 5-19B) provided with nine 
15-watt, 1-filament lamps. Six lamps are used in 
the top of the socket for the red light and three 
in the bottom for the white light; each light is 
energized from a separate circuit. 

The controller for the speed lights is located 
in the pilothouse and is energized through the 
supply switch on the signal and anchor light 
control and supply panel. The speed light system 
operates automatically when the circuit control 
switch is placed in the MOTOR PULSE position 
and the signal (speed) selector switch is set in 
the desired position. This action established con- 
nections to the motor-driven pulsator to provide 
the signals. 

STERN LIGHT. The stern light (blue) is a 
12-point (135^ light similar to the previously 
described white stern light. The light is installed 
near the stern on ships that are engaged in convoy 
operations and is mounted to show an unbroken 
arc of light from dead astern to six points on 
each side of the ship. 



FIXTURE 



MULTIPLE 
SOCKET 




A B 

AIRCRAFT WARNING LIGHT 



RED 




WHITE 



D MULTIPLE 
SOCKET 



C FIXTURE 



SPEED LIGHTS 



77.44 
Figure 5-19. Aircraft warning and speed lights. 



WAKE LIGHT, The wake light (white) is 
installed on the flagstaff or after part of the 
ship to illuminate the wake and is mounted so 
that no part of the ship is illuminated. The 
fixture is spraytight and of tubular construction. 
One end of the fixture is fitted with an internal 
screen, having a 1-inch diameter hole provided 



SHIPBOARD ELECTRICAL SYSTEMS 



with a lens through which light is emitted from 
a 100 -watt, 2-filament lamp. A suitable mounting 
bracket is included for adjusting the position of 
the light. Thus, the wake light puts a "target" 
in the ship's wake. 

SUBMARINE IDENTIFICATION LIGHT. The 
submarine identification light is displayed solely 
for identifying a craft on the surface as a sub- 
marine. Its display does not change any of the 
Rules of the Road nor confer any privilege on 
the ship showing it. The light is an amber 
rotating light producing 90 flashes per m:.nute, 
visible all around the horizon, and located approxi- 
mately 6 feet above the masthead light. 

REVOLVING BEAM ASW LIGHT. The re- 
volving beam ASW light (fig. 5-20) is displayed 
for intership signaling during ASW operations and 
is installed on all ships equipped to participate 
in ASW operations. The light is positioned on 
either the yardarm or mast platform where it 




^ 
Figure 5-20. ASW revolving beacon. 



27.367 



can best be seen all around the horizon. Two red, 
two green, and two amber lenses are provided 
with each fixture. Colors to be used are determined 
by operating forces. 

Signal Lights (Visual Communication) 

The signal lights for visual communication 
include the blinker lights located on the yardarm 
and the 8- and 12-inch searchlights. 

BLINKER LIGHTS. The blinker lights (white) 
are used in much the same manner as searchlights 
for communication but, because of their location, 
many ships can receive the message at the same 
time. They are located, one port and one starboard, 
outboard on the signal yardarm. The fixtures are 
spraytight, each provided with two clusters of six 
15- watt, 1 filament lamps. Cluster 41 may "be used 
singly for normal use. Through switching, cluster 
42 may be added to 41 to increase brilliance for 
communication at greater distance, or 4 2 may be 
selected alone if 1 fails. The lights are operated 
from signal keys located on each side of the 
signal bridge. 

SEARCHLIGHTS. Naval searchlights are 
used to project a narrow beam of light to illuminate 
distant objects. They are also used for visual 
signaling. To accomplish its purposes, the search- 
light must have an intense, concentrated source 
of light, a reflector that collects light from the 
source (to direct it in a narrow beam) , and a 
signal shutter (to interrupt the beam of light), 

Searchlights are classified according to the 
size of the reflector and the light source. The 
8-inch searchlight has an incandescent light 
source, and the 12-inch can have either an in- 
candescent or an inert gas light source. 

The 8-inch signaling searchlight utilizes an 
incandescent sealed beam lamp. It is designed to 
withstand high vibratory shock and extreme 
humidity conditions and will operate equally well 
in hot or cold climates. 

This searchlight may be furnished for opera- 
tion with either a 60-hertz, 115-volt transformer 
to step the voltage down to 23 volts, or without 
a transformer to operate on 115 volts using the 
proper rated sealed beam unit. The same unit 
is available for use on small craft from a 28-volt 
power source. 

The searchlight (fig. 5-21) consists of the 
(1) base, (2) yoke, (3) housing, and (4) lamp. 
The base is equipped with a rail clamp to secure 
the searchlight to the rail. The yoke is swivel- 
mounted on the base so that it can be trained 
through 360. The housing provides an enclosure 



86 



Chapter 5 SHIPBOARD LIGHTING 



CLAMP RING 



BACKSHELL 
HOUSING 



SHUTTER 
HOUSING 



BRACKET 




LAMP 



BASE CD 
RAIL CLAMP 



77.62 

Figure 5-21. 8 -inch 60 -hertz sealed -beam 
searchlight. 



Three filter assemblies (red, green, and 
yellow) are provided and can be readily snapped 
in place over the face of the searchlight. The 
shutter vanes can be locked in the open position 
for use as a spotlight. 

The backshell housing provides an enclosure 
for the 115/23-volt transformer. 

The 12-inch incandescent searchlight is used 
primarily for signaling and secondarily for illumi- 
nation. The searchlight (fig. 5-22) is comprised 
of (1) mounting bracket, (2) yoke, (3) drum, and 
(4) lamp (not shown). The mounting bracket 
permits the searchlight to be secured to a vertical 
pipe or to a flat vertical surface. The yoke is 
swi vel-m ounted on the bracket to allow the search- 
light to be rotated continuously in train. The steel 
drum provides housing for the lamp and is 
trunnion-mounted on the yoke to allow it to be 
elevated and depressed. Clamps are provided for 
locking the searchlight in any position of train 
and elevation,, 

The SIGNALING SHUTTER is a venetian-blind 
shutter mounted inside the drum behind the front 
door. It is held in the closed position by two 
springs and is manually opened by a lever 
on either side of the drum. The parabolic metal 
reflector is mounted on the inside of the rear 
door. 



for the lamp and is composed of a front and a 
rear section. The front section comprises the 
shutter housing, and the rear section comprises 
the backshell housing. The two sections are held 
together by a quick-release clamp ring that 
permits easy replacement of the lamp. The 
backshell and lamp assembly, when detached, 
may be used as a portable searchlight. The entire 
housing is mounted on brackets attached to the 
shutter housing and is supported by the yoke 
to allow the searchlight to be elevated or de- 
pressed. Clamps are provided to secure the 
searchlight in train and elevation. 

The shutter housing (fig. 5-21) contains the 
Venetian blind shutter, which is held closed by 
springs and is manually opened by a lever on 
either side of the housing. The front of the 
shutter housing is sealed by the cover glass 
and a gasket. The rear of the shutter housing 
is enclosed by a gasket and adapter assembly. 
The adapter assembly provides a locating seat 
for the lamp and incorporates a hook and key 
arrangement that aligns the backshell housing and 
retains it in position while attaching the clamp 
ring to hold the two sections together. 




SHUTTER 
LEVER 



DRUM 



YOKE 



MOUNTING 
BRACKET 



77.58 
Figure 5-22. 12-inch incandescent searchlight. 



87 



SHIPBOARD ELECTRICAL SYSTEMS 



The LAMP is usually a 1000-watt, 117-volt 
incandescent lamp having special concentrated 
filaments that reduce the area of the light 
beam. The lamp is mounted in a mogul bipost 
socket. The socket is located in front of the 
reflector and can be adjusted only slightly. 
The lamp can be replaced through the rear 
door of the searchlight. 

The light source must be at the focus of the 
reflector for minimum beam spread and maximum 
intensity. Some types of 12-inch incandescent 
searchlights are provided with focusing adjust- 
ment screws. Other types can be adjusted by 
loosening the screws that hold the lamp-socket 
support plate in position. Move the entire socket 
assembly toward or away from the reflector 
until the beam has a minimum diameter at a 
distance of 100 feet or more from the light, and 
retighten the screws. When checking the diameter 
of the beam, be sure the rear door is tightly 
clamped shut. 

A screen hood is provided for attachment 
to the front door to limit the candle power of 
the beam, to cut down its range, and to reduce 
stray light, which causes secondary illumination 
around the main beanie The hood also provides 
for the use of colored filters. 

The 12-inch mercury-xenon arc lamp (fig. 
5-23) has a 1000-watt short-arc and requires 
45 amperes to start and 18 amperes to operate. 
It is supplied from the ship's 117-volt, 60-hertz, 
single-phase power. The lamp consists of two 
tungsten electrodes spaced approximately 1/4 
inch apart inside a 2-inch diameter quartz 
bulb. The bulb contains a small quantity of 
liquid mercury and xenon gas at a pressure of 
3 to 5 atmospheres when the lamp is cold (an 
atmosphere at sea level is equivalent to 14.7 
psi). After the arc is started and the lamp attains 
a stable operating temperature, the internal 
pressure increases to approximately 20 atmos- 
pheres. The lamp does not produce full-light output 
until this pressure is reached and all of the mer- 
cury has been vaporized. The lamp differs from the 
incandescent lamp in that it requires a high volt- 
age, RF current for starting and a ballast for 
operating at rated output. Because of the high 
voltages involved and the high pressure of these 
lamps, safety precaution should be observed. 

The LAMP ADJUSTER ASSEMBLY is secured 
to the top of the searchlight drum and extends in- 
side the drum to provide a mounting for the 
mercury-arc lamp. The assembly affords longi- 
tudinal traverse (toward or away from the re- 
flector), horizontal (from side to side), and 
vertical adjustments of the lamp. 



LOCK 
SCREW 



I AMP ADJUSTER 
ASSEMBLY 



FOCUSING 
HAM OLE 



REAR 
DOOR 




MERCURY-XEN 

ARC LAMP 



SHUTT 

" LEVEi 



REFLECTOR 



71 
Figure 5-23. 12-inch mercury-xenon searchli 

The BALLAST UNIT, located out of 
weather near the searchlight, consists of 
transformer and five resistors enclosed ii 
steel box. The unit provides the necess 
ballast voltage in series with the lamp to ma 
tain constant current for normal operation. 

The STARTER UNIT, enclosed in a wat 
tight box, is mounted in the lamp housing 
consists of the necessary components for start 
and operating the lamp. The electrical connect! 
from the ballast unit to the starter unit 
provided by a cable equipped with a waterti 
Plug. 

When the lamp is extinguished, whether 
or cold, the internal resistance between electro 
is so high that the arc will not restart w! 
normal line voltage is applied. Hence, a spet 
high- voltage, RF circuit is incorporated to pro^ 
instant starting, irrespective of whether the la 
is cold or hot. However, the lamp is har 
to start while it is hot and at maximum intei 
pressure. The RF circuit is capable of produc 
a voltage from 40,000 to 60,000 volts. After 
arc is started, the lamp will operate on nori 
voltage of 60 to 70 volts. 

The ship's single-phase, 115-volt, 60-he 
power is supplied to the ballast unit through 
disconnect switch located adjacent to the sear 
light. 



88 



Chapter 5 SHIPBOARD LIGHTING 



INFRARED TRANSMITTERS. The infrared 
transmitters (beacons) are designed to operate 
in the infrared frequency spectrum. Because 
infrared radiation is invisible, these transmitters 
provide a means for signaling at night during 
darkened- ship conditions. The beacons are located 
on either side of the signal yardarm and may be 
operated separately or simultaneously by either 
of two manual keys. An infrared receiver is 
used by the receiving ship to observe the signal 
from the transmitting ship. 

MULTIPURPOSE SIGNAL LIGHT. The port- 
able multipurpose signal light (fig. 5-24) pro- 
duces a high intensity beam of light suitable 
for use as a spotlight or as a blinker (by means 



of a trigger switch located on the rear handle) 
for visual communications. The light is designed 
to operate from an internal battery (three type 
BA-2 dry cells connected in parallel), or from 
the 120-volt a.c. ship's supply via a 120/20-volt 
transformer mounted in the stowage box. The 
front handle is adjustable to assure a steady 
position for signaling, and front and rear sights 
provide for holding the beam on the desired 
target. 

Supplied with the light, in addition to the 
stowage box, are red, green, and yellow lenses, 
a 15-foot power cable for supplying power from 
the ship's a.c. source to the stowage box, a 
25-foot cable for supplying power from the 



FRONT SIGHT 



LAMP RETAINING 
RING 

LAMP GASKET 



SEALED-BEAM 
LAMP 



LATCH 



HOUSING 



FRONT 
HANDLE 




REAR 
SIGHT 



SPONGE 
RUBBER 
CUSHION 

LAMP 
SOCKET 

SWITCH 
PLATE 

SWITCH 
DPDT 



REAR 

HANDLE 

ASSEMBLE 



CONNECTOR 



' FORWARD POSITION 



101.5 



Figure 5-24. Multipurpose signal light. 
89 



SHIPBOARD ELECTRICAL SYSTEMS 



stowage box to the light, and the manufacturer's 
technical manual. 

Floodlights and Lanterns 

FLOODLIGHTS. The floodlight (fig. 5-25A) 
consists of a splashproof housing equipped with 
a rain-shielded, hinged door secured with a 
trunk type latch. The 300-watt lamp is the sealed- 
team type. The lamp housing is trunnioned on 



a yoke which in turn is mounted on a sho, 
absorbing base. The light is secured in elevatt 
by a clamp on the yoke. Train positioning 
accomplished by friction within the shock t 
sorbing base. Each floodlight is furnished witt 
3-conductor cable (including a green lead to gron 
the metal housing) for connection into the light! 
circuit. 

Larger 500 -watt floodlights (not shown), usi: 
a mogul screw base lamp, are also widely use 




FLOODLIGHT 





HAND LANTERN 
(MANUAL OPERATED) 




PORTABLE FLOOD LANTERN 



HAND LANTERN 
( RELAY OPERATED) 



Figure 5-25. Floodlights and lanterns. 
90 



77,* 



Chapter 5 SHIPBOARD LIGHTING 



Floodlights are installed on weather decks at 
suitable locations to provide sufficient illumi- 
nation for the operation of cranes and hoists, and 
the handling of boats. New high-level illuminating 
floodlights are being developed for evaluation by 
Naval Sea Systems Command,, 

Two types of dry battery lanterns are available 
for installation in certain strategic locations to 
prevent total darkness in case the lighting power 
fails. One model is hand operated. The other is 
operated automatically by a relay when the regular 
power fails. 

MANUALLY OPERATED HAND LANTERN. 
The manually operated hand lantern (fig. 5-25B), 
consists of a watertight plastic case containing 
two (6-volt) batteries connected in parallel. 
It includes a sealed beam lamp, rated at 5 
volts, but operated at 6 volts (when the batteries 
are new) to increase the light output. A rigid 
handle is secured to the top of the case. The 
lantern is operated by a toggle switch, the lever 
of which is convenient to the thumb. When the 
batteries are fresh, the lantern can be used 
continuously for approximately 8 hours before 
the light output ceases to be useful. 

Manually operated lanterns are installed as 
an emergency source of illumination in spaces 
that are manned only occasionally. These lanterns 
are also used in certain areas to supplement the 
relay-operated lanterns. 

Manually operated hand lanterns must not be 
removed from the compartments in which they 
are installed unless the compartments are to be 
abandoned permanently. 

RELAY-OPERATED HAND LANTERN. The 
relay-operated hand lantern is similar to the 
manually operated type except that the relay 
housing is mounted topside of the lantern case 
(fig. 5-25D) in place of the handle. The 115-volt 
a.c. version is identified by symbol 101.2. Symbol 
102.2 identifies the 115-volt d.c. type. A 3-con- 
ductor cable (including a green conductor to ground 
the relay metal frame) is provided for connection 
into the lighting circuit, THE RELAY-CON- 
TROLLED LANTERN MUST ALWAYS BE IN- 
STALLED WITH THE RELAY UPPERMOST. 
This specific arrangement of the relay prevents 
a proven fire hazard, which would be caused 
if the liquid electrolyte (formed from battery 
exhaustion) drained into the (otherwise inverted) 
relay housing. 

Relay- controlled lanterns are assigned to 
spaces which require practically continuous 
illumination. These spaces include essential watch 



stations, control rooms, machinery spaces, and 
battle dressing stations. The lanterns must illumi- 
nate the tops and bottoms of all ladders and 
flush-mounted scuttles. They must also be 
mounted so as to illuminate all gages at vital 
watch stations. Operating personnel will depend 
on these lanterns for illumination when bringing 
the machinery back on the line in the event of 
a casualty. These lanterns must not be installed 
in magazine or powder-handling spaces in which 
fixed or semifixed ammunition is handled, or in 
any location in which explosion-proof equipment 
is required. 

The lantern relay is connected in the lighting 
circuit (in the space in which the lantern is 
installed) on the power supply side of the local 
light switch that controls the lighting in the 
space concerned. Thus, the relay is operated 
and will restore, causing the lamp in the lantern 
to be energized from its batteries only when 
power failure occurs, but not when the lighting 
circuit is deenergized by the light switch. If 
the space is supplied with both emergency and 
ship's service lights, the lantern relay is con- 
nected to the emergency lighting circuit only. 

PORTABLE FLOOD LANTERN. The port- 
able flood lantern (fig. 5-25C) consists of a 
sealed beam lamp enclosed in a built-in lamp 
housing equipped with a toggle switch. The 
lamp housing is adjustably mounted on a drip- 
proof, acid-resistant case provided with two 
windows in each end. 

The case contains four Navy type BB-254/U 
storage cells. Each cell contains a channeled 
section in which a green, a white, or a red ball 
denotes the state of charge of the cell through 
a viewing window. When a cell is fully charged, 
all three indicator balls float at the surface of 
the electrolyte. The green ball sinks when approx- 
imately 10% of the cell capacity has been dis- 
charged; the white ball sinks when the cell is 
50% discharged; and the red ball sinks when the 
cell is 90% discharged. 

The lamp is rated at 6 volts but is operated 
at 8 volts to increase the light output. When 
operated with fully charged batteries, the lantern 
can be operated continuously for approximately 
3 hours without being recharged. The batteries 
should be recharged as soon as possible after 
the green ball (10 percent discharged) has sunk 
to the bottom. The lanterns should be checked 
at least once a week to determine whether the 
green indicator balls are floating. If they are not 
floating, the battery should be charged at a rate 
of 1 1/2 to 2 amperes until all indicator balls 



91 



SHIPBOARD ELECTRICAL SYSTEMS 



are floating at the indicator line. If the battery 
is completely discharged, it will require from 
20 to 25 hours to recharge it. After the charging 
voltage has remained constant at 10 volts for 1 
hour, discontinue the charging. 

When necessary, add pure distilled water 
to keep the electrolyte level at the indicator 
line marked on the front of the cell. Do not 
add enough water to bring electrolyte level 
above the line because overfilling nullifies the 
nonspill feature of the battery and may cause 
the electrolyte to spurt out through the vent 
tube. However, if the electrolyte level is not 
at the indicator line, the charge indicator balls 
will not indicate correctly the state of charge 
of the battery. 

Portable flood lanterns are often referred 
to as damage control lanterns because they are 
used by damage control personnel to furnish 
high intensity illumination for emergency repair 
work or to illuminate inaccessible locations 
below deck. 



MAINTENANCE 

The intensity of illumination produced by 
lighting installation begins to depreciate at ft 
time the system is placed into operation. Tt 
greatest loss of light (up to 30%) can usual! 
be attributed to dirt and oil on lamps an 
fixtures. A regular program of fixture and lam 
cleaning will improve illumination aboard yot 
ship. 

Burned out incandescent lamps may be dis 
posed of at sea, but for security reasons, 
must be remembered that incandescent lamps m 
float and therefore must first be broken. 

Fluorescent lamps contain mercury gas whic 
is poisonous. Therefore, all fluorescent lamp 
must be collected and turned into a shore-toast 
control point for land disposal. NO FLUOE 
ESCENT LAMPS SHALL BE DUMPED INT 
ANY BODY OF WATER, INCLUDING OCEAN: 



92 



CHAPTER 6 

DEGAUSSING 



A steel-hulled ship is like a huge floating 
magnet. Because of its magnetic field, the ship 
can act as a triggering device for magnetically 
sensitive mines. Degaussing concerns the methods 
and techniques of reducing the effects of the ship's 
magnetic field to minimize the possibility of 
detection by magnetic mines and other magnetic 
influence detection devices. 

The earth's magnetic field has various 
strengths throughout the earth's surface. The 
sensor of a magnetic mine is set to the strength 
of the earth's magnetic field at the mine's location. 
Now, if any ferrous metal is introduced into 
the earth's magnetic field near the mjne, the 
magnetic field around the sensor will be distorted, 
causing the mine to blow up. 

A steel ship which has received no anti- 
magnetic, or degaussing, treatment has a large 
magnetic field surrounding its hull. As the ship 
moves through the water, this field also moves 
and adds to, or subtracts from, the earth's mag- 
netic field causing it to bend or move. To a 
magnetic mine beneath the ship, this moving 
magnetic field (ship) appears as a change or 
variation in the surrounding magnetic environ- 
ment. Magnetic ordnance is highly sensitive 
to variations in the earth's magnetic field. When 
the ship is degaussed, its field is altered or 
modified so the ordnance can detect little, if any, 
magnetic disturbance as the ship passes. 



EARTH'S MAGNETIC FIELD 

The earth's magnetic field acts upon all 
metal objects on or near the earth's surface. 
Figure 6-1 shows the earth as a huge permanent 
magnet, 6000 miles long, extended from the arctic 
to the antarctic polar regions. Lines of force 
from this magnet extend all over the earth's 
surface, exerting a magnetic influence on all 



POINT 

EARTH'S FLUX LINES" 



EARTHS GEOGRAPHIC 
NORTH POLE 




[EARTH'S GEOGRAPHIC 
'SOUTH POLE 



EARTH AS A MAGNET 



27.104 



Figure 6-l Earth's magnetic fieldo 



ferrous materials that are on or near the surf ace * 
Since many of these ferrous materials them selves 
become magnetized, they distort the background 
field into irregular eddies and areas of greatly 
increased or decreased magnetic strength. Thus, 
the lines of magnetic force at the earth's surface 
do not run on straight, converging lines like the 
meridians on a globe, but appear more like the 
isobar lines on a weather map. 

By convention, the external direction of the 
magnetic field of a bar magnet is from the 
north pole to the south pole. Lines of force for 
the earth's field, however, leave the earth in the 
southern hemisphere and reenter in the northern 
hemisphere. Therefore, we must think of the 
polar region in the arctic as the north-geographic, 
south-magnetic pole, which describes the di- 
rection of polarity used in the field of degaussing. 

Note in figure 6-1 that the magnetic meridians 
form closed loops, arching from the earth's 



93 



SHIPBOARD ELECTRICAL SYSTEMS 



magnetic core to outer space and reentering the 
earth in the opposite hemisphere. Since all lines 
of magnetic force return to their points of 
origin, they form closed magnetic circuits. An 
idea of the size of the earth's magnetic field 
is apparent when you notice that lines of force 
at the polar regions seem to extend vertically 
into space. The size Of the closed loops formed 
by these lines of force is staggering to the 
imagination. It is impossible to eliminate the 
earth's field; however, the effects of the ship 
on this field may be lessened. Degaussing limits 
the ship's distortion of the earth's magnetic field, 
and some highly developed techniques are used 
in the process. 

The strength and direction of the earth's field 
at any point is a function of the strength of the 
individual components. The angle of the field 
with the horizontal, sometimes called the dip, 
may be easily determined by a dip needle, a simple 
compass needle held with the needle pivot axis 
parallel to the earth's surface. Since a compass 
needle always aligns itself parallel to the lines 
of force of a magnetic field, the dip needle indi- 
cates the angle of the earth's field to the hori- 
zontal by aligning itself with the lines of force 
entering or leaving the earth at that point. Both 
direction and strength of the field may be deter- 
mined by means of a mine search coil and flux- 
measuring equipment. 

Since the earth's field can be resolved into 
two components, the horizontal (H) component 
and the vertical (Z) component, the vector sum of 
the H and Z components will define the magnitude 
and the direction of the total field at any point 
on the earth's surface. The force of the magnetic 
flux can be resolved into a horizontal and a 
vertical component as shown in figure 6-2. 

Table 6-1 shows horizontal and vertical 
component strength, and the resulting total field 
strength and direction for several representative 
geographical locations in the northern and the 
southern hemispheres*, Note that the vertical 
component may be assigned either a positive or 
negative value because lines of force leave the 
earth in the southern hemisphere and reenter 
in the northern hemisphere. Therefore, the upward 
field in the southern hemisphere is assigned 
a negative value, and the downward field in 
the northern hemisphere is assigned a positive 
value. There are two areas of maximum vertical 
intensity but opposite polarity the north and 
south magnetic poles. The vertical intensity at 



FLUX 
LINE 



H=R COS 6 



S. 
GEOGRAPHIC 




N. 
GEOGRAPHIC 



H AND 2 COMPONENTS 



27.104 

Figure 6-2. Horizontal and vertical components 
of earth's magnetic field. 



the magnetic equator is zero since the entte 
field is horizontal*. 



SHIP'S MAGNETIC FIELD 

The magnetic field of a ship is the re sultan 
of the algebraic sum of the ship's permanen 
magnetization and the ship's induced magnet- 
ization. The ship's magnetic field may have an) 
angle, with respect to the horizontal axis of to 
ship, and any magnitude. 



SHIP'S PERMANENT 
MAGNETIZATION 

The process of building a ship in the present 
of the earth's magnetic field develops a certaii 
amount of permanent magnetism in the ship 
The magnitude of the permanent magnetizatio: 
depends on the earth's magnetic field at theplac; 
where the ship is built, the material of whic! 
the ship is constructed, and the orientatia 
of the ship at time of building with re spec 
to the earth's field. 



94 



Chapter 6 DEGAUSSING 



Table 6-1 . Measurements of the earth's magnetic field at selected locations 



LOCATION 


HORIZONTAL (H) 
COMPONENT 


VERTICAL (Z) 
COMPONENT 


TOTAL FIELD 
STRENGTH 


DIRECTION OF 
TOTAL FIELD 


North Pole (Magnetic) 





+620 


620 


90 down 


Fairbanks, Alaska 


120 


+560 


570 


78 down 


Stockholm, Sweden 


150 


+460 


490 


70 down 


London, England 


190 


+440 


470 


69 down 


Washington, D.C. 


180 


+540 


570 


72 down 


Tokyo, Japan 


300 


+340 


460 


50 down 


Manila, Philippine Islands 


390 


+100 


410 


14 down 


Equator (Magnetic) 


410 





410 


horizontal 


Rio de Janeiro, Brazil 


230 


-080 


250 


20 up 


Capetown, South Africa 


140 


-280 


320 


64 up 


Buenos Aires, Argentina 


230 


-140 


260 


30 up 


Melbourne, Australia 


230 


-560 


610 


68 up 


South Pole (Magnetic) 





-720 


720 


90 up 



NOTE-A11 measurements are approximate. 



27.378 



The ship's permanent magnetization can be 
resolved into the (1) vertical permanent field 
component and (2) the horizontal permanent 
field component. The horizontal permanent field 
component can be resolved into the longitudinal 
permanent field component and the athwartship 
permanent field component. The vertical, longi- 
tudinal, and athwartship permanent field com- 
ponents of the ship are virtually constant and 
are not affected by changes in heading or magnetic 
latitude. 



SHIP'S INDUCED 
MAGNETIZATION 

Any piece of iron in a magnetic field will 
have magnetism induced in it. Therefore a ship, 
by its very existence in the earth's magnetic 
field, has a certain amount of magnetism induced 
in it The ship's induced magnetization depends 
on the strength of the earth's magnetic field and 
on the heading of the ship with respect to the 
earth's field. 



All ships that are fitted with shipboard de- 
gaussing installations, and other ships that do 
not require degaussing installations, are de- 
permed. Deperming is essentially a large-scale 
version of demagnetizing a watch. The purpose 
is to reduce permanent magnetization and bring 
all ships of the same class into a standard 
condition so that the permanent magnetization, 
which remains after deperming, is approximately 
the same for all ships of that class. 



Thie ship's induced magnetization, like the 
ship's permanent magnetization, can be resolved 
into the (1) vertical induced field component and 
(2) the horizontal induced field component. The 
horizontal induced field component is also com- 
prised of the longitudinal induced field component 
and the athwartship induced field component. 

Table 6-1 shows the force of the earth's 
field which causes magnetic induction on the ship. 
Therefore, the magnitude of vertical induced 



95 



SHIPBOARD ELECTRICAL SYSTEMS 



magnetization depends on the magnetic latitude. 
Remember the vertical induced magnetization is 
maximum at the magnetic poles and zero at the 
magnetic equator. 

The vertical induced magnetization is directed 
downward whenever the ship is north of the 
magnetic equator and upward whenever the ship 
is south of the magnetic equator* Hence, the 
vertical induced magnetization changes with mag- 
netic latitude, and to some extent, when the 
ship rolls or pitches. The vertical induced 
magnetization does not change with heading be- 
cause a change of heading does not change the 
orientation of the ship with respect to the vertical 
component of the earth's magnetic field, 

The longitudinal induced magnetization 
changes when either the magnetic latitude or the 
heading changes and when the ship pitches. If a 
ship is headed in a north-geographic direction, 
the horizontal component of the earth's magnetic 
field induces a north pole in the bow and a south 
pole in the stern (fig. 6-3A). In other words, the 
horizontal component of the earth's field induces 
a longitudinal, or fore-and-aft, component of 
magnetization. The stronger the horizontal com- 
ponent of the earth's magnetic field, the greater 
will be the longitudinal component of magnet- 
ization. If the ship starts at the south magnetic 
pole and steams toward the north magnetic 
pole, the longitudinal component of induced mag- 
netization starts at zero at the south magnetic 
pole, increases to a maximum at the magnetic 



equator, and decreases to zero at the north 
magnetic pole. Hence, for a constant heading 
the longitudinal component of induced magnet- 
ization changes when the ship moves to a position 
where the horizontal component of the earth's 
magnetic field is different that is, when the 
ship changes its magnetic latitude. 

If at a given magnetic latitude the shij 
changes headings from north to east, the longi- 
tudinal component of induced magnetization wil 
change from a maximum on the north headinj 
to zero on the east heading. When the shi] 
changes heading from east to south, the longitu- 
dinal component increases from zero on the eas 
heading to a maximum on the south heading 
On southerly headings a north pole is induce 
at the stern and a south pole at the bow, whic 
is the reverse of the conditions on northerl 
headings,, The longitudinal component of induce 
magnetization also changes, to some exten 
as the ship pitches. 

The athwartship induced magnetizatic 
changes whenever either the magnetic latitude c 
the heading changes, and whenever the ship roll 
or pitches. When a ship is on an east headinj 
a north pole is induced on the port side and 
south pole on the starboard side (fig. 6-3B 
which is the athwartship component of indue* 
magnetization. The magnitude of the athwart sh 
magnetization depends on the strength of tl 
horizontal component of the earth's magnet 
field at that latitude. This component is maxima 



1 NORTH 
\ \ l GEOGRAPHIC 




I NORTH I 
GEOGRAPHIC 




A. LONGITUDINAL MAGNETIZATION B, ATHWARTSHIP MAGNETIZATION 
OF A SHIP. OF A SHIP. 



Figure 6-3. Effect of the earth's magnetic field upon a ship. 



27.105: 



Chapter 6 DEGAUSSING 



at the magnetic equator for a ship on an east- west 
heading and zero at the magnetic poles for a 
ship on a north-south headingo 



MAGNETIC RANGES 
AND RANGING 

A magnetic range is a station equipped to 
measure the magnetic field of ships which pass 
over measuring equipment located at or near 
the bottom of the channel in which the ships 
travel. The magnetic range is more commonly 
called a Degaussing Range or Degaussing Station. 

A ship is said to be ' 'ranged* ' when its 
magnetic field is measured at a magnetic range 
Ranging has two classifications: calibration 
ranging and check ranging. 

CALIBRATION RANGING 

Calibration ranging provides information for 
degaussing charts, determines initial degaussing 
coil current, and indicates whether changes or 
modification to the ship's degaussing installation 
are required. 

CHECK RANGING 

Check ranging determines the adequacy of 
current settings and the performance of de- 
gaussing equipment as well as personnel. 

For accurate ranging the ship must pass 
directly over the range at a constant speed and 
heading. The degaussing coils must be set cor- 
rectly in accordance with the values given in the 
degaussing folder. For depth correction, the 
range officer must be notified of coil settings 
and of the ship's draft, forward and aft, to the 
nearest 6 inches 

DEGAUSSING FOLDER 

The ship's Degaussing Folder is a record of 
the degaussing installation in the ship The folder 
contains (1) a description of the degaussing 
installation, (2) a record of inspections, tests, 
and repairs performed by repair activities, (3) 
the values of all coil currents for the ship's 
positions and headings, and (4) a record of the 
degaussing range runs. The Degaussing Folder 
is necessary to the operation of the degaussing 
system and must be safeguarded against loss. 
Generally, the Degaussing Folder is in the 
possession of the navigator. The engineer officer 



provides the navigator with the names of engi- 
neering personnel who will require access to the 
folder. 

The Ship's Force Degaussing Maintenance 
Record, NAVSHIPS 1009, is a record of the 
maintenance performed on the degaussing system 
by the ship's force. When completed, the forms 
are inserted in the Degaussing Folder. 



BASIC OPERATION OF 
SHIPBOARD DEGAUSSING 

A coil of wire with current passing through 
it will produce a magnetic field whose polarity 
and magnitude are dependent on the amount 
and direction of current flow. A shipboard de- 
gaussing installation consists of one or more 
of these coils in specific locations aboard ship 
and a means to control the magnitude and direction 
of the current through the coils. Compass- 
compensating equipment, consisting of compen- 
sating coils and control boxes, are also installed 
as a part of the degaussing system to compensate 
for the deviation effect of the degaussing coils 
on the ship's magnetic compasses 

DEGAUSSING COILS 

The distortion of the earth's field caused 
by the ship's permanent magnetization (vertical, 
longitudinal, and athwartship components) and 
the ship's induced magnetization (vertical, longi- 
tudinal, and athwartship components) is neutral- 
ized by means of degaussing coils. The degaussing 
coils are made with either single-conductor or 
multiconductor cables. The coils must be ener- 
gized by direct current, which is supplied from 
120-volt or 240-voltd.c. ship's service generators 
or from degaussing power supply equipment in- 
stalled for the specific purpose of energizing 
the degaussing coils. 

The degaussing coils consist of coils of 
cable wound on the ship, each having the correct 
location and the required number of turns to 
establish the required magnetic field strength 
when energized by direct current of the proper 
value and polarity. The coils will then produce 
magnetic field components equal and opposite to 
the components of the ship's field. Each coil 
consists of the main loop and may have smaller 
loops within the area covered by the main loop, 
usually at the same level. The smaller loops 



97 



SHIPBOARD ELECTRICAL SYSTEMS 



oppose localized peaks that occur in the ship's 
magnetic field within the area covered by the 
main loop. The resultant effect of the degaussing 
coils, when the currents are properly set, re- 
stores the earth's field to the undistorted condition 
around the shipo 

M Coil 

The M or main coil (fig, 6-4A) encircles the 
ship in a horizontal plane usually near the water- 
line. The M coil counteracts the magnetic field 
produced by the vertical permanent and the ver- 
tical induced magnetization of the ship (fig 6-5) . 
Hence, the M coil current must be changed 
when the ship changes magnetic latitude in order 
to keep the M coil field as nearly as possible 
equal and opposite to the field produced by the 
ship's vertical induced magnetization The per- 
manent vertical magnetization of a ship remains 
constant o 





'M FIELD 1 


v^ 

A 


^__^^ ^ M COIL ^^^/ 


M COIL 



Q_COIL OR QI 
AND QP COILS 



F-COIL, OR FI 
AND FP COILS 



L FIELD 



B 




F ANDQ COILS 



'L FIELD 



L COIL LOOPS 




L COIL 



FIELD 




F and Q Coils 

The F or forecastle coil (figo 6-4B) encirc] 
the forward one-fourth to one-third of the si 
and is usually just below the forecastle 
other uppermost deck; whereas, the Q or quarte 
deck coil encircles the after one-fourth to or 
third of the ship and is usually just below 1 
quarterdeck or other uppermost deck The 
and Q coils counteract the magnetic field pi 
duced by the ship's longitudinal permanent i 
longitudinal induced magnetization The shg 
of the magnetic field produced by the F anc 
coils is somewhat different from the magne 
field produced by the ship's longitudinal ma 
netism, but, in general, the two fields are oppos 
and directly below the bow and stern of the si 
(figo 6-6). The F and Q coil currents mast 
changed when the ship changes its course 
magnetic latitude in order to keep the c 
strengths at the proper values to counteract i 
changes in the ship's longitudinal induced 1112 
netization. Two adjustments are necessary, one 
change the F coil current and the other to char 




MAGNETIC FIELD 

INDUCED BY VERTICAL MAGNETIZATION 
OF SHIP 




-M COIL 



MAGNETIC FIELD 
INDUCED WHEN M 
COIL IS ENERGIZED WITH POSITIVE POLARITY 



27.; 

27.107 Figure 6-5. Effects of induced vertical magneti 
Figure 6-4. Types of degaussing coils. and M coil magnetism. 



98 



Chapter 6 DEGAUSSING 




LONGITUDINAL 
FIELD OF SHIP 



NORTH 



27.370 

'igure 6-6 . Longitudinal field of ship and neutral- 
izing fields of F-Q coils. 



he Q coil current. In many installations the 
conductors of the F and Q coils are connected 
o form two separate circuits designated as the 
r I-QI coil and the FP-QP coil (fig. 6-4B). 

The FI-QI coil counteracts the magnetic field 
iroduced by the ship's longitudinal induced mag- 
letization. The longitudinal induced magnetization 
Changes when the ship changes heading or magnetic 
atitude, and the FI-QI coil current must be 
changed accordingly. 

The FP-QP coil counteracts the magnetic 
ield produced by the ship ' s longitudinal perm anent 
nagnetization. The longitudinal permanent mag- 
tetization does not change when the ship changes 
Leading or magnetic latitude; therefore, no change 
s needed in the strength of the FP-QP coil. 

, Coil 

The L or longitudinal coil (fig. 6-4C) consists 
>f loops in vertical planes that are parallel to 
he frames of the ship. The coil counteracts the 
oagnetic field produced by the ship's longi- 
udinal permanent and longitudinal induced mag- 
tetization. The L coil is more difficult to install 
han the F and Q coils or the FI-QI and FP-QP 
soils, but provides better neutralization because 
t more closely simulates the longitudinal mag- 
Letization of the ship. The L coil is commonly 
.sed in minesweeper vessels. 

The longitudinal induced magnetization changes 
/hen the ship changes heading or magnetic lat- 
tude; therefore, the L coil current must be 
hanged accordingly. Aboard a minesweeper, the 
a coil current must even be changed as the 



vessel pitches. Roll or pitch adjustments, or 
both, are necessary on all the degaussing coils 
aboard minesweepers. 

A Coil 

The A or athwartship coil (fig. 6-4D) consists 
of loops in vertical fore-and-aft planes. The A 
coil produces a magnetic field that will counter act 
the magnetic field caused by the athwartship 
perm .anent and athwartship induced m agnetization. 
The athwartship induced magnetization changes 
when the ship changes heading or magnetic 
latitude; therefore, the A coil (current) must be 
changed accordingly. 



MANUAL DEGAUSSING 
SYSTEMS 

Degaussing installations, as previously stated, 
consist of different combinations of degaussing 
coils and manual or automatic degaussing equip- 
ment to control the current in these coils. The 
selected combination depends on the size and the 
intended use of the particular ship. 

The current in the A coil and in the FI-QI 
or F and Q coils must be changed whenever 
there are changes in the ship's heading or in 
the magnetic latitude, or both. Current in the 
coils is controlled manually in the older in- 
stallations and automatically in all newer in- 
stallations. Current in the M and FP-QP coils 
remains essentially constant with the current 
in the M coil changing only when the ship changes 
zones and the current in the FP-QP coil changing 
only as a result of calibration. 

Degaussing installations that control the coil 
currents manually are energized from constant 
voltage d.c. generators or from variable voltage 
motor-generators and are called rheostat and 
motor-generator installations, respectively. 

Reversing switches are used to change the 
polarity of the coils, except when provision for 
the change has been made in the design of the 
rheostat of the constant voltage supply or in the 
generator control of the variable voltage supply. 

RHEOSTAT CONTROL 

In a rheostat degaussing installation the power 
for the degaussing coils is supplied by a constant- 
voltage d.c. generator; the coil currents are 
controlled by adjusting a rheostat connected 
in series with the coil and power supply. An 
installation using rheostats to control the M, 



SHIPBOARD ELECTRICAL SYSTEMS 



FI-QI, and FP-QP coil currents is illustrated 
in figure 6-7. Some installations use manually 
operated rheostats while others use motor- 
operated rheostats. In the manual type, the 
rheostat is adjusted locally at the degaussing 
switchboard by turning the rheostat handle. In 
the motor-operated type, the rheostat shaft is 
turned by a motor which is controlled from a 
remote station by a push button. Motor-operated 



rheostats are equipped for manual operation 
the event of an emergency . 

MOTOR-GEN ERATOR 
CONTROL 

In a motor-generator degaussing installatj 
the power for the degaussing coils is suppl 
by a motor-generator; the coil currents \ 



REMOTE READING 
AMMETERS 



FI-QI COIL 
ft REMOTE 
T REVERSING 
SWITCH 



120 OR 240 
VOLT D.C. 
SUPPLY BUS 



OP-COIL 



POWER 
SUPPLY 
LEADS TO 
COMPENSATING 
CIRCUITRY (CCCJ, 




77, 



Figure 6-7. -Manual degaussing system with rheostat control. 

100 



Chapter 6 DEGAUSSING 



controlled by adjusting a rheostat in the generator 
field circuit to vary the output of the generator. 
A single-line diagram of this type installation 
is illustrated in figure 6-8. The rheostats in the 
generator fields can be operated either manually 
or by a motor to change the generator voltage 
and thereby adjust the coil current to the desired 
value. 

POLARITY 

The polarity of the degaussing coil currents 
is of particular importance. If the polarity of 
any of the degaussing coils is incorrect, the ship 
may be in much greater danger from magnetic 



mines than if no degaussing were installed. The 
coils, instead of cancelling the magnetic field, 
would be adding to it. The polarity of a coil 
should be checked as to whether the pointer of 
the ammeter for the coil is on the POSITIVE 
(right) or NEGATIVE (left) side of the zero-center 
ammeter. Also, the polarity of a coil can be 
checked by observing whether the positive or 
negative plate glows in the neon indicator light 
for the coil. For positive polarity the right-hand 
electrode glows, and for negative polarity the 
left-hand electrode glows* 

The direction of current (polarity) can also 
be checked by a degaussing polarity indicator or 
a small compass. The polarity indicator dial 



AMMETER 
INDICATOR LIGHT? 
PUSH BUTTON 



REMOTE CONTROL 
PANEL 



AMMETER 

MOTOR STARTING PUSH BUTTON 

RHEO. PUSH BUTTON 

TRANSFER SWITCH 
LOCAL CONTROL PANEL 



MOTOR 



T TO COMPASS 
COMPENSATING 
COILS 



TO COMPASS 

COMPENSATING 

COILS 



TO COMPASS 
COMPENSATING 
COILS 




MOTOR 



.-^-RHEOSTAT > DRIVEN 
IN GEN. I RHEO. 
FIELD 



Figure 6-8.- M, F, and Q coil installation with motor-generator control. 

101 



77.182 



SHIPBOARD ELECTRICAL SYSTEMS 



is marked to denote the direction of current,, 
When taking polarity readings with the indicator 
or small compass, move the device toward the 
degaussing coil until a good deflection is obtained, 
and no closer. The needle in the indicator or 
compass will reverse its magnetic polarity if 
the device is held too closely to the coils. The 
indicator or compass should be checked after 
each test to ensure that the magnetic polarity of 
the needle has not reversed. 



CHANGING COIL 
CURRENTS 



The Degaussing Folder for each ship gives the 
current needed for each coil at all positions on 
the earth's surface and at all headings. One or 
more of the coil currents must be changed when 
one of the following conditions occurs: 



1. When the ship passes from one Z zone 
to another. 

The vertical intensity (Z component) of the 
earth's field, which is maximum at the magnetic 
poles and zero at the magnetic equator, is divided 
into a number of Z zones. The number of Z 
zones will vary, depending on the amount of com- 
pensation provided by the particular installation. 
Degaussing Chart No. 1 (fig. 6-9) illustrates 
the Z zones for the Atlantic and Indian Oceans. 
The reverse side of this chart (not shown) 
contains the same number of Z zones for the 
Pacific Ocean. The coil settings are filled in 
(lower left of chart) for the various zones 
after the ship has been ranged. 

2. When the ship passes from one H zone 
to another. 



3. When the ship's heading changes fron 
one sector to another. 



The entire range of headings from to 360 
is divided into a number of sectors, each coverin; 
a part of the whole range of courses. 

The Degaussing Course Corrections Settinj 
Diagram No. 1 for the FI-QI coil and Diagrac 
No. 2 for the FI-QI and A coils are illustrate 
respectively in figures 6-11 and 6-12. 

The Degaussing Course Correction Setting 
Table No. 1 for the F and Q coils and Table 
No. 2 for the F, Q, and A coils are illustrated 
respectively in figures 6-13 and 6-14. 



None of the degaussing coil currents are 
changed as long as the course remains in one 
sector, that is, the Z zone and H zone remain 
unchanged. The FP-QP coil current is NOT 
changed when the ship's heading or the ship's 
position changes. The following changes are 
necessary when changing from one sector to 
another or from one zone to another: 



1. The M coil current must be changed when 
the ship moves from one Z zone to another. The 
M coil current is NOT changed when the ship 
moves from one H zone to another or when the 
heading changes from one sector to another, 

2. The F, Q, FI-QI, L, and A coil currents 
are not changed when the ship moves from one 
Z zone to another, but must be changed when 
the ship moves to a different H zone, or when 
the heading changes to a different sector. 



The horizontal intensity (H component) of the 
earth's magnetic field, which is maximum at 
the magnetic equator and zero at the magnetic 
poles, is divided into a number of H zones. 
Similar to the Z zones, the number of H zones 
will vary, depending on the degree of compensation 
provided by the degaussing system. Degaussing, 
Chart No. 2 (fig. 6-10) illustrates the H zones 
for the Atlantic and Indian Oceans and the reverse 
side (not shown) contains the same number of H 
zones for the Pacific Ocean. 



AUTOMATIC DEGAUSSING 
SYSTEMS 



As we have discussed, current changes are 
necessary to produce the correct strength of 
magnetism at different headings. You can imagine 
how very time consuming, with inescapable human 
error, it would be if personnel had to make the 
calculations for the current changes and take 



102 



Chapter 6 DEGAUSSING 




tf< 

iH 



CO 



SHIPBOARD ELECTRICAL SYSTEMS 




104 



Chapter 6 DEGAUSSING 



DEGAUSSING 

COURSE CORRECTION SETTING DIAGRAM No. 1 

MANUAL OPERATION 

FI-QI COIL 

HEADINGS ARE MAGNETIC 
N 





SWITCH IN NORTH 

POSITION 
(CURRENT POSITIVE) 



SWITCH IN EAST-WEST POSITION 
(CURRENT OFF) 



SWITCH IN SOUTH 

POSITION 
(CURRENT NEGATIVE) 





THE CURRENT IN THE FI-QI COIL IS TURNED ON (POSITIVE) FOR NORTHERLY COURSES, 
OFF FOR EASTERLY AND WESTERLY COURSES, AND REVERSED (NEGATIVE) FOR SOUTHERLY 
COURSES BY MEANS OF A SWITCH ON THE BRIDGE OR IN THE CHART HOUSE. 

WHEN THE SHIP IS ON A NORTHERLY HEADING SET THE CURRENT IN THE FI-QI COIL 
AT THE VALUE SHOWN IN DEGAUSSING CHART NO. 2 MANUAL FOR THE LOCATION OF 
THE SHIP AT THE TIME. WHEN THE COURSE IS SOUTHERLY THE CURRENT SHOULD BE THE 
NEGATIVE OF THIS VALUE. 

CHANGE THE CURRENT VALUE IF THE SHIP MOVES INTO A DIFFERENT ZONE. 

IN EMERGENCY, WHEN COURSE CHANGES ARE TOO RAPID TO FOLLOW, SET SWITCH 
IN EAST-WEST POSITION. 



(Supersedes NAVWEPS 8950/46F) 



MAVSHIPS 8950 /1UF (REV. 3-67) 
DG NO. 12 



69.16 



Figure 6-11. Degaussing course correction setting diagram No. 1. 



corrective action. To eliminate these disad- 
vantages, a control system was designed to 
utilize the primary course indicating equipment 
already aboard ship, the gyrocompass, in con- 
junction with the degaussing coils. This system 
is the automatic degaussing system. 



There are many types of automatic degaussing 
systems but they all use the same basic concepts 
of operation. We shall describe the SSM system 
which differs from older systems by the manner 
in which the current is controlled and sent to 
the degaussing coils. The SSM uses solid state 



105 



SHIPBOARD ELECTRICAL SYSTEMS 



WNW 
290' 



WSW 
250 



3. 



DEGAUSSING 
COURSE CORRECTION DIAGRAM NO. 2- A 

MANUAL OPERATION 
HEADINGS ARE MAGNETIC 



FI-QI 



COIL(S) 



^COIL(S) 




mi HID 



SWITCH TO 
POSITIVE CURRENT 
(NORTH HEADING) 



NNW 
340 



N 



SWITCH TO CURRENT OFF 
(EAST-WEST HEADING) 



SWITCH TO 
NEGATIVE CURRENT 
(SOUTH HEADING) 



n w 




ESE 
110 



SWITCH 

TO 

NEGATIVE 
CURRENT 

(WEST 
HEADING) 



SWITCH 

TO 
CURRENT 

OFF ) 
(NORTH- 
SOUTH : 
HEADING) 



NNE 

020 



SWITCH 

TO 

POSITIVE 
CURRENT 

(EAST 
HEADING) 




ssw 

S 200 

DEGAUSSING COIL HEADING SWITCH MUST BE KEPT IN POSITION 
CORRESPONDING TO MAGNETIC HEADING OF SHIP IN ORDER TO OBTAIN 
PROPER CURRENT POLARITIES AND MAGNITUDES. 

THE SETTINGS OR CURRENT VALUES ARE OBTAINED PROM DEGAUSSING 
CHART NO. 2-S MANUAL. SWITCH POSITIONS REQUIRED DURING SET-UP 
OF CURRENTS ARE: 



FI-QI 



_COIL(S), NORTH POSITION 
_COIL(S), .EAST POSITION 



IN EMERGENCY, WHEN COURSE CHANGES ARE TOO RAPID TO FOLLOW, 
TURN COILS OFF TO WHICH THIS SWITCH APPLIES.. 



(Supersedes NAVVEPS 8950/46G) 



NAVSHIPS 89 50 /l*6 (REV. 3-67) 
DG NO. 13 



Figure 6-12. Degaussing course correction setting diagram No. 2. 



69.17C 



devices rather than the magnetic amplifiers in 
older types. 

SSM AUTOMATIC 
DEGAUSSING SYSTEM 

The SSM automatic degaussing system controls 
the current in four independent degaussing coils. 
"*- system (fig. 6-15 and 6-16) is made up of the 



, 
degaussing switchboard, FI-QI coil power supply, power supply. 



FP-QP coil power supply, A coil power supplj 
]VI coil power supply, and a remote control unil 

Degaussing Switchboard 

The degaussing switchboard receives 450 VA( 
from ship's power and generates a refereno 
signal, proportional to the ship's position an 
heading, which controls the output of each coi 



106 



Chapter 6 DEGAUSSING 



DEGAUSSING 
COURSE CORRECTION SETTING TABLE N2 I. 

( F AND Q COILS ) 

MANUAL OPERATION 




This Table is to be used in ALL regions. 



INSTRUCTIONS FOR USE = 

By rtfrtnc to Dtgouing Chart N02. 9<ct th circle diagrams btlow whtfb correspond to thr M zone for 
th position of th chip . The actual ttttingt to b uMd or thin found in th oppropriot* count loctort. 



M ZONE 

.115 



SETTINGS BELOW ARE IN AMPERES /AMPERE TURNS 
HEADINGS ARE MAGNETIC 




'Strike out whatever is not applicable. 



NAME OF SHIP 

uss 


u. s. 


PORT OF 1 SSUE 

TfQM TWT PAPTTTTY 


DATE 

2 May 69 


UDC* UrAor* r Av/Xijl.i.i'* 


ctxc,o^ 



(Supersedes NAVWEPS 8950- 46D) 



NAVSHIPS 8950/I^D (REV. 3-67) 
DG NO. 10 



Figure 6-13. Degaussing course correction setting table No. 1. 

107 



69.17D 



SHIPBOARD ELECTRICAL SYSTEMS 



DEGAUSSING 

COURSE CORRECTION SETTING TABLE NO. 2 



(F,Q, AND A COILS) 
MANUAL OPERATION 



NORTHERN 



This Table is to be used ONLY when the ship is in the 

Degaussing Chart No. 1. Separate Tables are provided for the other two regions. 



_ region shown on 



INSTRUCTIONS FOR USE: 

By reference to Degaussing Chart No. 2 select the circle diagrams below which correspond to the H zone for the position of the ship. 
The actual settings to be used are then found in the appropriate course sectors. 



SETTINGS BELOW ARE IN AMPERES/AMPERE TURNS ' 
HEADINGS ARE MAGNETIC 




,r<rrminTFnTh>^ 






FOR OTHER ZONES (OVER) 




NAME OF SHIP 

uss - - 


NATION 

U.S. 


PORT OF ISSUE 

USN DEG* FACILITY 


DATE 

2 May 1969 




*?.&.Qrt 



*Strike out whatever is not applicable. 



(Supersedes NAVWEPS 8950/46E) 



NAVSHIPS89SO/14E (REV. 3-67) (FRONT) 

OG NO. 11 B-33548 



Figure 6-1 4. Degaussing course correction setting table No, 2 (Front), 

108 



69.171 



Chapter 6 DEGAUSSING 



REMOTE 
CONTROL ASSEMBLY 




Figure 6-15. SSM Automatic Degaussing System. 



27.371X 



Manual Channels (M & FP-QP) 

The manual channels, M and FP-QP, located 
in the degaussing switchboard, generate a 
reference signal by applying 24 VDC to the 
induced magnitude potentiometer shown in 
darkened line on figure 6-1 7 . The wiper arm 
on the potentiometer is adjusted to obtain the 
desired signal in accordance with the ship's 
Degaussing Folder. The polarity is selected 
by the position of the manually operated polarity 



switch. Only the M coil channel is shown in figure 
6-17. 



Automatic Channels (A & FI-QI) 

The two automatic channels, A and FI-QI, also 
located in the degaussing switchboard, are identi- 
cal with the exception of a permanent bias current 
that can be applied to the A coil and not to the 
FI-QI (fig. 6-18). The permanent bias current 



109 



SHIPBOARD ELECTRICAL SYSTEMS 




110 



Chapter 6 DEGAUSSING 



DEGAUSSING SWITCHBOARD 




27.373 



Figure 6-17. Manual Channel (M coil). 



compensates for the permanent athwart ship com- 
ponent of the ship's magnetism* The settingof the 
permanent bias is found in the ship's Degaussing 
Folder. 

When either or both of the automatic channels 
are switched to the manual mode, the reference 
signal, magnitude, and polarity are determined 
by the setting of the heading switch. 



Figure 6-19 shows the A coil only.* In the 
automatic mode a signal is applied to the dif- 
ferential transmitter synchro TDX, which modi- 
fies the true heading signal. The magnetic 
variation dial is manually operated to adjust 
the magnetic heading signal in accordance with 
the known magnetic variation for the particular 
area in which the ship is operating. The mag- 
netic signal is then applied to the synchro 



111 



SHIPBOARD ELECTRICAL SYSTEMS 



DEGAUSSING SWITCHBOARD 




Figure 6-18. Automatic channel, manual operation* 



27.374 



receiver TR, which will turn the magnetic heading 
indicator and the resolver. The resolver breaks 
the magnetic heading signal into two separate 
signals, one representing the sine, the other 
the cosine of the magnetic heading angle. The 
sine signal is used for the A coil, the cosine 
for the FI-QI coil. The automatic induced poten- 
tiometer establishes the maximum level to be 
operated in the automatic mode. Also fed into 
the demodulator and output amplifier are the 
permanent bias (for the "A" channel only) 
and the H-zone setting. An error sensor also 
compares the input and output signals to the 
demodulator. Any difference will activate an 
error signal light on the degaussing switchboard. 



The four reference signals that are developed 
by each coil channel are supplied to the corre- 
sponding power supply. 



Coil Power Supplies 

The coil power supplies contain silicon con- 
trolled rectifiers. You will find a discussion on 
the workings of these devices helpful in under- 
standing the operation of the power supplies. 

An SCR is a semiconductor device which can 
be gated (turned on) during any portion of the 



112 



Chapter 6 DEGAUSSING 



DEGAUSSING SWITCHBOARD 



MAGNETIC 

HEADING 

INDICATOR 




27.375 



Figure 6-19 . Automatic channel, automatic operation (A coil only). 



positive half-cycle of an a.c. signaL Refer to 
figure 6-20A If the gate pulse fires at the 
start of the half-cycle, the SCR will continue 
to conduct during the entire half-cycle. If the 
gate pulse fires 90 later (fig. 6-20B), the SCR 
will conduct on only half of the half-cycle. There- 
fore, we can control the firing rate of the SCR's 
by controlling the gate pulse and thereby control 
the output with a small signal. 

This concept is used in the SSM degaussing 
coil power supplies. Please note in figure 6-21 
that the signal developed by the channel in the 
degaussing switchboard goes through an isolation 
amplifier to electrically isolate it from the 



switchboard and the other three coil power 
supplies. The signal then goes to a regulator 
which also receives a current feedback signal 
from the coil. The signals are compared and 
then sent to the firing logic circuits. The firing 
logic circuits control the basic firing angle 
for the SCR's to control the output current An 
error sensor compares the input and output 
signals in the same manner as the error sensor 
in the degaussing switchboard. 



Two other types of automatic degaussing 
systems installed aboard ships are the GM-1A 
and the SM-9A. The basic principles of operation 



SHIPBOARD ELECTRICAL SYSTEMS 



PHASE DELAY 
MAX OUTPUT 
GATE PULSE 




PHASE DELAY 90 
HALFMAX OUTPUT 




CONDUCTION ANGLE 



27.376 
Figure 6-20. Operation of silicon control rectifier. 



are the same as for the SSM, therefore, we si 
give only a brief description of the two systei 

GM-1A AUTOMATIC 
DEGAUSSING SYSTEM 

The GM-1A automatic degaussing syst 
consists of nine units; a degaussing switchboa 
an automatic control unit (installed in the swit 
board), a degaussing remote control panel, 1 
rectifier power supplies (M coil and FP- 
coil power supplies), two motor-generator s 
(FI-QI coil and A coil), and two magnetic c< 
trollers which are used only with the A c 
and FI-QI respectively. As illustrated in figi 
6-22, the FP-QP coil power supply may 
either of two sizes, 3kWor 5kW, having diffen 



DEGAUSSING 
SWITCHBOARD 



SILICON 
CONTROLLED 
RECTIFIER 
ASSEMBLY 




450V AC 30 60Hz 



Figure 6-21, Coil power supply. 
114 



27.37? 



Chapter 6 DEGAUSSING 






1 

O 



8 
I 

LJ 

r 




GC 

I 

1: 
S, 



o: -3 
P 



00 
CO 





S 

t 



o 

T3 





o 
o 

o 

=3 

S 

I 



<M 
CD 





o: 

o 



QC 
Ltl^. 

p 



O 

I 



115 



SHIPBOARD ELECTRICAL SYSTEMS 



-. ._.* *mw -. f - -- ___. >..- j_ jt. X^A V/WJL.LO iJLA V^ClDv? bill 

paving different output ratings. automatic equipment fails, the FI-QI and the 1 

T.^^ Systeiri provides automatic degaussing coil can also be controlled manually (Em er gene 1 

rents for the FT-OT coil and the A coiL Manual^ ' 



AIIT. * 

currents for the FI-QI coil and the A coil, 



450 VOLT 60 Hz 

3 PHASE POWER 

12O VOLT 400 Hz 

POWER 

GYRO SIGNAL 




F.l'QI DEGAUSSING COIL 



FP-QP 
POWER 
SUPPLY 



FP-QP DEGAUSSING COIL 



FP-Q.p FI.ELD 
FI-QI FIELD 



Figure 6-23. -Type SM-9A automatic degaussing control system. 



77.32'i 



Chapter 6 DEGAUSSING 



SM-9A AUTOMATIC 
DEGAUSSING SYSTEM 

The SM-9A automatic degaussing control sys- 
tem comprises a degaussing switchboard (fig. 
6-23), a remote switchboard, and FI-QI coil power 
supply, an FP-QP coil power supply, and an M 
coil power supply* 



Degaussing Switchboard 

The degaussing switchboard (fig. 6-24) con- 
tains the controls required to operate the de- 
gaussing system o The FI-QI control panel mounted 
at the top of the switchboard contains all the 
circuits required to control the FI-QI degaussing 
currents in both the manual and automatic 
modes of operation. The M control panel mounted 
in the center left section of the switchboard 
contains the controls and circuitry required 
to control the M coil current. The FP-QP 
control panel mounted center right contains 
the controls for setting the FP-QP coil current. 
At the bottom is located the power supply over- 
heating alarm circuits and ground fault detector. 

The remote control unit has three meters 
which indicate the current in each of the three 
degaussing coils. Three red lights mounted on 
the unit indicate whether there is trouble in any 
of the three circuits. One white light indicates 
that the system is in manual operation, and 
another indicates that the FI-QI current is 
being controlled at the remote control unit by 
the manual control switch on the remote unit. 

The three power supplies contain the circuits 
necessary to supply the currents to degauss 
the ship. The only externally mounted -com- 
ponents on the power supplies are indicator type 
fuses which fuse the power circuits in the supplies. 



LOCAL 

CONTROL 

UNIT 



M 

CONTROL 
PANEL 



FP-QP 

CONTROL 

PANEL 




GROUND FAULT 
DETECTOR PANEL 




111.121 
Figure 6-24. Degaussing switchboard. 



117 



CHAPTER 7 



AUXILIARY SHIPBOARD EQUIPMENT 



Personnel assigned to the electrical divi- 
sion(s) maintain a variety of auxiliary equipment. 
Much of this equipment is vital to the ship's 
operation, and muoh of it is very complex in 
nature. In this chapter we shall discuss the basic 
operating principles of some of this equipment. 



BATTERIES 

Many types of equipment aboard ship utilize 
batteries as their source of direct current 
electricity. Such equipment includes portable 
announcing equipment, portable and emergency 
lighting equipment, ship's boats, dial telephone 
systems, gyrocompass systems, and many others. 
In some instances batteries are used as the only 
source of power, while in others, they are used 
as a secondary or standby power source. 

A battery consists of one or more cells con- 
nected together to function as a source of elec- 
trical power. 

PRIMARY CELL 

A primary, cell consists of two dissimilar 
materials (electrodes) immersed in acid. As a 
broad definition, a primary cell is one in which 
the chemical action eats away one of the elec- 
trodes, usually the negative. When this happens, 
the electrode must usually be replaced or the 
cell must be discarded. The dry cells employed 
in flashlights are common examples of primary 
cells. 

SECONDARY CELL 

Generally, a secondary cell is one in which 
the electrodes and the electrolyte are altered 
by the chemical action that takes place when 
the cell delivers current. These cells may be 
restored to their original condition by forcing 
an electric current through them in the direction 
opposite to that of discharge. The automobile 



storage battery is a common example ol 
secondary cell. 

Cells are connected together to provide 
amount of voltage and current required of 
battery. As an example, the common l2-\ 
automobile battery consists of 6 cells, & 
cell producing approximately 2 volts. 

TYPES OF BATTERIES 

There are many different types of batteri 
in use today, however, most of them are us 
in special applications and are not commor 
found in shipboard electrical equipment. 

The dry cell, lead-acid and nickel- cadmiu 
batteries are toy far the most common types 
use aboard ship today. The material present! 
in this chapter, though not all inclusive, pr< 
vides the reader with a general view of the* 
various types of batteries. 

Dry Cell 

The common carbon- zinc dry cell batter] 
so-called because its electrolyte is not in 
liquid state, is used in flashlights and battl 
lanterns. Actually, the electrolyte is a rnois 
paste. If it should become dry, it could m 
longer transform chemical energy to electrica 
energy. The name dry cell, therefore, is no 
strictly technically correct. 

CONSTRUCTION OF THE DRY CELL, Tto 
construction of a common type dry cell is showi 
in figure 7-1. The internal parts of the cell 
are located in a cylindrical zinc container which 
also serves as the negative electrode of the 
cell. A carbon electrode is located in the center 
and serves as the positive terminal of the 
cell. The paste electrolyte is a mixture oi 
several substances. Its composition may vary, 
depending on its intended use and manufacturer, 



118 



Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT 



POSITIVE 
TERMINAL 



STEEL 
COVER 



NEGATIVE 
TERMINAL 

EXPANSION 
CHAMBER 



PASTE 
ELECTROLYTE 



ZINC CAN 

(NEGATIVE 

ELECTRODE) 




ASPHALT 
SATURATED 
PAPER GASKET 

ASPHALT 
SATURATED 
INSULATING 
WASHER 

(4-) CARBON 
ELECTRODE 

PASTE COATED 

PULPBOARD 

SEPARATOR 

CHIPBOARD 
JACKET 



236.28 



Figure 7-1. Cutaway view of a dry cell. 



Binding posts are attached to the electrodes 
so that wires may be conveniently connected 
to the cell. 

CHEMICAL ACTION OF THE DRY CELL. 
The action of the electrolyte on the carbon and 
zinc electrodes of the dry cell produces an 
electrical current flow when the cell is con- 
nected to a load. In the process of producing 
the electrical current, the chemical action eats 
away the zinc container (negative electrode). In 



the process of being discharged, it is common 
for the zinc container to be sufficiently eaten 
away that the electrolyte will leak from the cell. 
The electrolyte is corrosive and will destroy 
the internal parts of electrical or electronic 
equipment with which it comes in contact. 

To prevent damage to electrical equipment 
from leaking electrolyte, dry cells should be 
replaced immediately after they have been dis- 
charged beyond their usable service life. 



119 



SHIPBOARD ELECTRICAL SYSTEMS 



Battery-powered equipment should NEVER 
be placed in stowage until the dry cells have 
been removed. 

SHELF LIFE OF THE DRY CELL. A cell 
that is not being used (on the shelf) will gradually 
deteriorate because of slow internal chemical 
actions (local action) and changes in moisture 
content. However, this deterioration is usually 
very slow if cells are properly stored. High- 
grade cells of the larger sizes should have a 
shelf life of 1 year or more. Smaller size 
cells have a proportionately shorter shelf life, 
ranging down to a few months for the very 
small sizes. If unused cells are stored in a 
cool place, their shelf life will be greatly in- 
creased; therefore, to minimize deterioration, 
unused cells should be stored in refrigerated 
spaces (10 to 35 F) that are not dehumidified. 



Secondary (Wet) Cells 

Secondary cells function on the same basic 
chemical principles as primary cells. They 
differ mainly in that they may be recharged, 



whereas the primary cell is not normally a 
charged. Some of the materials of a prima 
cell are usually consumed in the process < 
changing chemical energy to electrical euerg 
In the secondary cell, the chemical reaction thi 
produces the electricity does not consume tt 
electrodes, but it does usually change the chemici 
composition of the electrodes. Discharged sec 
ondary cells may be restored (charged) to the! 
original state by forcing an electric currei 
from some other source through the cell i 
the direction opposite that of discharge. 

There are many different types of secondai 
cells. Of these types, the lead-acid is the moi 
widely used. 

LEAD-ACID BATTERY. A lead- acid battei 
consists of a number of lead-acid cells connectc 
together, the number depending upon the voltag 
desired. Each cell produces approximately 
volts. 

A lead-acid battery (fig. 7-2) consists of 
hard rubber, plastic, or bituminous materi* 
compartment into which is placed the cell elernenl 
consisting of the positive and negative lead plates 
The plates are insulated from each other I 



CELL CONNECTOR 



FILLER OPENING 
IN CELL COVER 



VENT PLUG 

TERMINAL POST 

TERMINAL CONNECTOR 




CASE 



RIB 



236.3- 



Figure 7-2. Lead- acid battery. 
120 



Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT 



suitable separators (usually made of porous 
plastic, rubber, or glass) and submerged in a 
strong sulfuric acid solution (electrolyte). 

Many batteries are assembled in a one-piece 
container with compartments provided for each 
cell. The cells are covered with the same 
material as the battery container. Openings are 
provided in the covers for the terminals and 
the vent plug. 

The terminals of a lead- acid battery are 
normally distinguishable from one another by 
their physical size and by the markings of the 
manufacturer. The positive terminal, marked + f 
is slightly larger than the negative terminal, 
marked -. In addition, the terminals are some- 
times color coded red for the positive terminal 
and black for the negative terminal. 

Vent plugs are of various designs to permit 
the escape of gases that form within the cells 
while preventing leakage or loss of the electro- 
lyte. 

It is important that the openings of the vent 
plugs do not become clogged with dried elec- 
trolyte and dirt. If this should happen, pressure 
sufficient to burst the battery case could build 
up inside the cells while they are being charged. 

Lead- Acid Battery Operation. The active 
materials in a charged lead- acid battery are 
lead peroxide (the positive plate) and sponge 
lead (the negative plate). The electrolyte is a 
mixture of sulfuric acid and water. The strength 
(acidity) of the electrolyte is measured in terms 
of its specific gravity. Specific gravity is the 
ratio of the weight of a given volume of electro- 
lyte to an equal volume of pure water. 

As the battery discharges, the acid in contact 
with the plates separates from the electrolyte 
and forms a chemical combination with the active 
material of the plates changing them to lead 
sulfate. Thus, as the discharge continues, lead 
sulfate forms on the plates, and more acid is 
taken from the electrolyte. The water content of 
the electrolyte becomes progressively higher; 
that is, the ratio of water to acid increases. 
As a result, the specific gravity of the electrolyte 
will gradually decrease during discharge. 

If the discharged cell is properly connected 
to a direct-current charging source (the voltage 
of which is slightly higher than that of the cell) , 
current will flow through the cell in the direction 
opposite that of discharge, and the cell is said 
to be charging. The effect of the current changes 
the lead sulfate on both the positive and negative 
plates back to the original active form of lead 
peroxide and sponge lead, respectively. At the 



same time the sulfate is restored to the elec- 
trolyte, thereby increasing the specific gravity 
of the electrolyte. When all the sulfate has been 
restored to the electrolyte, the specific gravity 
will be maximum. The cell is then fully charged 
and is ready to be discharged again. 

During the battery charging operation quan- 
tities of hydrogen and oxygen gases are generated 
within the cell. If these gases are not vented, 
the cell container may burst; therefore, the 
gases must be vented to the atmosphere through 
the vent plugs. 

A mixture of hydrogen and air can be danger- 
ously explosive. No smoking, electric sparks, 
or open flames should be permitted near charging 
batteries. 

If a lead-acid cell or battery is allowed to 
remain in a discharged condition for more than 
24 hours, the lead sulfate on the plates hardens 
and it becomes increasingly difficult for the 
charging action to restore it back to the elec- 
trolyte. If allowed to remain in a discharged 
state for an excessive period of time, the cell 
cannot be restored to its original charged con- 
dition. Lead-acid cells should be maintained as 
near a fully charged condition as possible. 

You should also remember that sulfuric acid 
added to a discharged lead-acid cell will NOT 
recharge the cell and, in fact, can damage the 
cell. Added acid only increases the specific 
gravity of the electrolyte; it does not convert 
the lead sulfate on the plates back into active 
material (sponge lead and lead peroxide) and, 
consequently, does not bring the cell back to a 
charged condition. A charging current must be 
passed through the cell to do this. 

Only pure water should be added to a cell 
to maintain the electrolyte at the proper level. 

Specific Gravity. As the lead-acid cell dis- 
charges, the plates convert to lead sulfate, the 
sulfuric acid concentration in the electrolyte 
becomes weaker, and the specific gravity of 
the electrolyte approaches that of water (1.000). 

A hydrometer (fig. 7-3) is used to measure 
the specific gravity of the electrolyte, thereby 
determining the charge/discharge state of a 
lead-acid cell. The electrolyte of the cell being 
checked is drawn up into the glass tube by means 
of the rubber bulb at the top. The specific 
gravity of the electrolyte is read from the 
calibrated scale, which lies axially along the 
body of the float. 

There are several factors that may cause 
inaccuracies in hydrometer readings. The spe- 
cific gravity of the electrolyte is affected by 



121 



SHIPBOARD ELECTRICAL SYSTEMS 



1150 
DISCHARGED 




Figure 7-3. Hydrometer. 



236.39 



its temperature. When heated, the electrolyte 
expands, becoming less dense and its specific 
gravity reading is lowered. Conversely, when 
cooled, the electrolyte contracts, becoming 
denser and its specific gravity reading is raised. 
Thus, effects of temperature will distort the 
readings. 

When a reading is taken, the electrolyte in 
a cell should be at the normal level. If the level 
is below normal, sufficient fluid cannot be drawn 



into the tube to cause the float to rise. Ii: 
level is above normal, there is too much wait 
the electrolyte is weakened, and the read 
will be too low. 

A hydrometer reading is inaccurate if tali 
immediately after water has been added, becaii 
the water tends to remain at the top of the eel 
When water is added, the battery should be charge 
for at least 1 hour to mix the water with ti 
electrolyte before a hydrometer reading is take 

CAUTION: Hydrometers should be flush 
daily with freshwater to prevent inaccurate rea; 
ings. Lead- acid battery hydrometers must! 
be used for any other purpose. 

Battery Capacity. Batteries are rated i 
their ampere-hour capacity at a definite us 
of discharge. Most Navy portable lead-acid IE 
teries, except those used in aircraft, are rats 
at a 10-hour discharge rate. The capacity t 
the battery, then, varies with how it is discharge 
in relation to its rated discharge rate. For ei 
ample: Suppose a battery is rated at 200 ampeit 
hours (will supply 20 amperes constantly to 
load for 10 hours),, As shown in the table belo* 
if it is discharged in less than 10 hours, it vS 
deliver less than its rated ampere-hour capacit) 



Discharge time 

1 hour 

2 hours 

3 hours 
6 hours 

10 hours 



Percentage of 
ampere-hour 
capacity delivered 

55% 
65% 
75% 
90% 
100% 



Types of Lead- Acid Battery Charges, -I 
general, battery charges are used to initial! 
activate a battery or to restore a battery to ife 
charged state. The following types of charge 
may be given to a lead-acid battery, depended 
on the condition of the battery and PMS require- 
ments: 

1. Initial charge 
2 Normal charge 

3. Equalizing charge 

4. Float charge 

5. Emergency charge 

When a new battery is shipped dry, ft 
plates are in an uncharged condition. After flif 
electrolyte has been added, the battery is give: 
a long, low- rate, initial charge to convert tfe 



Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT 



plates into the charged condition. The charge is 
given in accordance with the manufacturer's in- 
structions, which are shipped with each battery. 
If the manufacturer's instructions are not avail- 
able, the charge should be made in accordance 
with detailed instructions in current directives. 

A normal charge is a routine charge, given 
in accordance with the nameplate data during 
the ordinary cycle of operation, to restore the 
battery to its charged condition. 

An equalizing charge is an extended normal 
charge, given periodically to ensure that all 
the sulfate is driven from the plates and to 
restore the electrolyte to its maximum specific 
gravity. 

The floating charge is used to maintain a 
battery at its fully charged condition. In this 
type of charge, the battery is connected to a 
charging voltage that is slightly higher than 
the battery voltage, and the battery is charged 
.constantly. The floating charge is usually used 
on batteries that are used as standby power 
sources for equipment such as dial telephones 
or gyrocompasses. 

The emergency charge is used when a battery 
must be recharged in the shortest possible time. 
The charge starts at a much higher rate than 
is normally used and should be used only in an 
emergency because this type charge may be 
harmful to the battery. 

Normally, the rate at which Navy lead-acid 
batteries are charged is given on the battery 
nameplate. If the available charging equipment 
does not have the desired charging rates, the 
nearest available rates should be used. However, 
the rate should never be so high that violent 
gassing occurs. NEVER ALLOW THE TEM- 
PERATURE OF THE ELECTROLYTE IN ANY 
CELL TO RISE ABOVE 125 F. 

NICKEL-CADMIUM BATTERIES. Nickel- 
cadmium batteries are made in both wet and 
dry cell forms. Both forms are used in appli- 
cations where lead-acid and conventional dry 
cell batteries are employed. 

Nickel-cadmium cells are generally superior 
to lead- acid or dry cells: 

1. In dry cell form they are longer lasting, 
capable of delivering more power per unit size, 
and may be recharged. 

2. In wet cell form they are lighter, deliver 
more power per unit size and require less 
maintenance. 



The main disadvantage of the nickel-cadmium 
battery is its high cost relative to conventional 
dry cells and the lead- acid battery. 

Nickel-Cadmium Cell Construction. The 
active materials of the nickel-cadmium cell 
(fig. 7-4) consist of nickel hydroxide on the 
positive plate and cadmium hydroxide on the 
negative plate. The electrolyte used in a nickel- 
cadmium battery is a caustic alkaline solution 
consisting of potassium hydroxide in distilled 
water. Chemically speaking, this is just about 
the exact opposite to the diluted sulfuric acid 
used in the lead- acid battery. 

The electrolyte of the nickel-cadmium cell 
conducts current between the negative and positive 
plates and reacts with them to produce electro- 
chemical changes without producing any sig- 
nificant change in its own chemical composition. 
For this reason, it is not possible to determine 
the charge state of a nickel-cadmium battery by 
checking the electrolyte with a hydrometer; 
neither can the charge be determined by a 
voltage test because of the inherent characteristic 



TERMINALS 



VENT AND 
FILLER CAP 




CASE 



SEPARATORS 



PLATE 



Figure 7-4. Nickel- cadmium cell. 



236.40 



SHIPBOARD ELECTRICAL SYSTEMS 



that the voltage remains constant during 90 per- 
cent of the discharge cycle. 

BATTERY MAINTENANCE 

In general, the maintenance required to main- 
tain any battery is dependent on its use. Some 
general information relating to the care, handling, 
and stowage of batteries is listed below. For 
detailed information relating to the maintenance 
and safety precautions for lead-acid and dry cell 
batteries, the manufacturer's technical manual, 
Naval Ships' Technical Manual, Chapter 313 
(9622), or the PMS should be consulted. For 
detailed information relating to nickel-cadmium 
batteries, maintenance and safety precautions as 
well as other alkaline batteries, the technical 
manual furnished with the battery, Naval Aircraft 
Storage Batteries, NAVAIR 17-15BAD-1, or the 
PMS should be consulted. 

Dry Cell Maintenance 

The common carbon- zinc dry cell battery is 
popular largely because it is essentially main- 
tenance free and very inexpensive. When used 
beyond serviceable life, these batteries are 
usually disposed of. 

Alkaline versions of the dry cell are becoming 
increasingly popular in commercial as well as 
Navy equipment. The batteries are supplied as 
sealed units. They are usually kept on float 
charge by a battery charger built into the equip- 
ment in which they are installed. Maintenance 
is not usually required on these batteries and, 
as with the common dry cell, they are usually 
replaced when beyond their service life. 

Because of chemical reactions within them, 
common dry cells deteriorate with age whether 
or not in use (25% to 50% energy is lost in 2 
yearSo) Deterioration may be minimized by 
storing dry cells in a cool location that is not 
dehumidified. 

Lead- Acid Battery 
Maintenance 

Although the PMS specifies minimum pre- 
ventive maintenance for lead- acid batteries, con- 
sideration should also be given to the application 
and conditions under which the battery is used. 

ENGINE STARTING BATTERIES. - Because 
of the heavy demands on batteries used for 
starting propulsion engines, ship's boat engines, 
ship's service and emergency engine- generator 



sets, they are particularly liable to failure, 
Defects, which would hardly be noticeable in 
a battery used for less severe service, could 
result in total failure in an engine starting 
sequence. Because these batteries are sometimes 
subjected to the severities of salt spray and cold 
weather, as in the ship's boats, they should 
receive an increased amount of attention. You 
will find it exceedingly difficult to explain to 
your commanding officer why the ship's life boat 
engine will not turn over or why the ship's 
emergency generator will not start. These bat- 
teries therefore require frequent checking ty 
competent personnel. 

Batteries subjected to cold weather should 
be kept fully charged because: 

1. Engines are harder to crank in cold 
weather. 

2. The electrolyte, being part water, can 
freeze, causing damage to the battery and case, 
As a rule, the greater the percentage of acid 
in the electrolyte, the lower its freezing tem- 
perature. As an example, electrolyte with a 
specific gravity of 1.150 (equivalent to that found 
in a discharged battery) will freeze at -15 
F s while electrolyte with a specific gravity of 
1.300 will remain unfrozen at temperatures down 
to -95 F, 

Grounds may be formed by dirt or acid on 
battery tops and sides. The ground path, through 
which current flows, can Tbe established from 
the battery terminals through the acid and dirt 
along the top and sides to the ship's hull, 

Battery grounds are undesirable becauset 

1. A ground in the vicinity of a battery may 
furnish the spark necessary to ignite an ex- 
plosive gas mixture, if present. 

2. A ground on the battery may cause a 
malfunction in the circuit to which the battery 
is connected. 

3. Leakage current from the battery through 
the ground can cause dissipation of the energy 
in the battery. 

In addition to forming grounds, dirt on battery 
tops and sides permits leakage current to flow 
directly from one terminal through the dirt and 
acid to the other terminal. This condition also 
dissipates the energy of the battery. 

For the reasons stated above, batteries must 
be kept clean. All electrolyte, dirt, salt, corro- 
sion, and foreign objects should be kept off 
battery tops and sides. Dirt and foreign material 



124 



Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT 



on the top of a battery case increase the like- 
lihood of their falling into the battery and con- 
taminating it when the vent plugs are removed. 
In this respect, the presence of salt and saltwater 
merit special concern of maintenance personnel 
because chlorine gas is released when salt and 
sulfuric acid are combined. 

Nickel- Cadmium 
Battery Care 

The majority of nickel- cadmium batteries 
under the cognizance of the electrical division(s) 
are an integral part of electrical or electronic 
equipment which, as a rule, have built-in battery 
chargers that maintain the nickel-cadmium bat- 
tery fully charged. These batteries are not 
usually subjected to severe usage but are used 
to supply power for a limited period to the equip- 
ment in case of normal power failure. 

Maintenance for the units should be carried 
out as prescribed in PMS. 

Dry Cell Safety 
Precautions 

1. When equipment operated by dry batteries 
is to remain idle for more than 2 weeks, the 
batteries should be removed and either scrapped 
or stored. 

2. Mercury-cell batteries may explode if 
improperly used. To prevent this occurrence, 
the following additional precautions must be 
followed: 

a. NEVER discharge a mercury-cell bat- 
tery after the battery fails to operate the equip- 
ment, or after the voltage falls below 0.9 volts 
per cell. 

b. NEVER leave the battery switch "on" 
when the equipment is not in use, or after the 
battery fails to operate the equipment. 

c. NEVER impose a "dead short circuit 15 
on a mercury cell, or allow it to become over- 
heated. A temperature of approximately 400 
F is sufficient to cause a mercury cell to 
explode. 

d. Mercury-cell batteries that have 
reached the end of their shelf- life while in storage 
should NEVER be issued to using activities. 

e. Discard exhausted mercury-cell bat- 
teries as soon as possible. Dead single and 
multicell mercury batteries with steel jackets 
should have holes punched in the jackets before 
being discarded to release any gas which might 
have formed. 



Lead- Acid Battery 
Safety Precautions 

1. Keep flames and sparks of all kinds away 
from the vicinity of lead- acid batteries. 

2. Be sure to ventilate battery compartments, 
which have been sealed, BEFORE entering the 
compartment, turning on any lights, making or 
breaking any electrical connections, or doing any 
work in the compartment. 

3. Be sure the ventilating apparatus of the 
battery compartment is runningproperly BEFORE 
starting a charge. 

4. STOP the charge if ventilation is inter- 
rupted, except in an emergency, and DO NOT 
resume the charge until ventilation has been 
restored. 

5. Charge a battery at the rates given on 
its nameplate. 

6. When charging lead-acid batteries, NEVER 
allow the cell temperature to exceed 125 F. 

7 Keep the temperature of the battery com- 
partment below 95 F, if at all possible. 

8. Make NO repairs to battery connections 
while current is flowing. NEVER connect or 
disconnect batteries on the charging line without 
first turning off the charging current. 

9. When using tools around a battery, be 
careful NOT to short circuit the battery terminals. 

10. When mixing electrolyte, always pour the 
acid slowly into the water; NEVER pour the 
water into the acid. Guard skin and eyes against 
splashes of acid with face shields, aprons, and 
rubber gloves. 

11. DO NOT store pure sulfuric acid in places 
where temperatures below 50 F may be en- 
countered. 

12. Keep the electrolyte level above the tops 
of separators. 

13. Add only pure distilled water to a battery. 

14. DO NOT, except in an emergency, discharge 
the battery below the given low-voltage limit. 

15. NEVER allow a battery to stand in a 
completely discharged condition for more than 
24 hours. 

16. DO NOT operate the battery when it reaches 
125 F. 

17. All sparks should be avoided during re- 
moval or replacement of batteries which are 
located in compartments that may contain gasoline 
fumes. Only tools with insulated handles should 
be used. For batteries that are used with one 
terminal grounded, the grounded terminal should 
be disconnected first when the battery is removed 
and connected last when the battery is being 
replaced. 



125 



SHIPBOARD ELECTRICAL SYSTEMS 



18. NEVER allow saltwater to enter a battery 
cell because the interaction produces extremely 
toxic chlorine gas. Also, saltwater should NEVER 
be used to wash battery cases and jars, 

19 Be sure all terminal connections are tight 
to preclude sparks due to loose connections. 

If acid or electrolyte from a lead- acid battery 
comes into contact with the skin, the affected 
area should be washed as soon as possible with 
large quantities of freshwater, followed with an 
application of a salve such as petrolatum, boric 
acid, or zinc ointment. If none of these salves 
is available, clean lubricating oil will suffice. 
When washing the affected area, large amounts 
of water should be used because a small amount 
of water might do more harm than good in 
spreading the acid burn. 

If acid splashes into the eyes, flush them 
immediately with large quantities of freshwater. 

Report to sickbay as QUICKLY as possible. 

Acid spilled on clothing may be neutralized 
with dilute ammonia or a solution of baking soda 
and water. 

Nickel-Cadmium Battery 
Safety Precautions 

The electrolyte used in nickel-cadmium 
batteries is a strong caustic alkaline solution of 
potassium hydroxide as opposed to the sulfuric 
acid solution used in lead-acid batteries. There- 
fore, the antidotes used when parts of the body 
are affected with potassium hydroxide will differ 
from those used when parts of the body are 
affected by sulfuric acid. 

If the alkaline electrolyte gets on the skin, 
wash the affected areas with large quantities 
of water, or take a shower immediately. Neutral- 
ize with a 3 percent solution of acetic acid and 
water, vinegar, or lemon juice, and wash with 
water. 

If the alkaline electrolyte gets into the eyes, 
flush them immediately with large quantities 
of freshwater and wash the eyes with a weak 
solution of boric acid, or a weak solution of 
vinegar. 

If alkaline electrolyte has been taken inter- 
nally, drink large quantities of water and a 
weak solution of lemon juice, orange juice, or 
vinegar; follow with white of egg, olive oil, 
melted butter, starch water, or mineral oil. 

In all cases seek medical attention IMME- 
DIATELY. 

As with lead-acid batteries, the electrolyte 
used in the nickel-cadmium battery is corrosive. 



Serious burns will result if the electrolyte 
comes in contact with any part of the body. Ust 
rubber gloves, rubber apron, and protects 
face shield when handling electrolyte. 

Nickel- cadmium batteries should not Tbe stored 
or serviced in the same areas with lead-aoM 
batteries. DO NOT use the same tools, such as 
screwdrivers, wrenches, syringes, hydrometers 
and gloves for both battery types. 



BATTERY CHARGING 
EQUIPMENT 

The battery charging equipment employed by 
the Navy varies from the very small circuits 
that provide the very low charging current to 
float charge small nickel-cadmium batteries used 
in electronic devices to the large motor- 
generator and engine-driven generators used 
to charge submarine storage batteries. 

Battery charging equipment must be capable 
of supplying voltages higher than that of the 
battery that is to be charged, and must be capable 
of supplying current commensurate with the 
battery's charging rate. 

The most common types of shipboard battery 
charging equipment are the battery charging sys- 
tems employed on ship's boats and the general 
purpose battery chargers. 

The battery charging systems employed in 
the ship's boats are very similar to the systems 
found in automobiles except that in most cases 
they are designed to charge 24-volt batteries and 
most automobile batteries are rated at 12 volts, 
These systems consist of engine-driven gener- 
ators or alternators which produce a d.c. voltage 
which is slightly higher than the battery voltage, 

During the first several minutes of operation, 
the boat battery-charging system charges the 
battery to its full capacity to replace all the 
energy that was used to start the engine. After 
this initial period the charging system continues 
to charge the battery, supplying sufficient current 
to maintain it on a float charge. In addition to 
charging the battery, the charging system must 
supply power to all the electrical loads on the 
boat, while the engine is running. 

The general purpose battery chargers em- 
ployed aboard ships consist of the devices neces- 
sary to convert the ship's alternating current 
to a controlled direct current of the proper voltage 
to charge batteries. These battery chargers are 
usually capable of charging batteries rated at 
various voltages. 



Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT 



The general purpose battery chargers are 
used to charge batteries that are not installed in 
systems with integral battery chargers. In addi- 
tion, they are used to provide supplemental 
charges to some batteries. For example, the 
batteries in the ship's boats are subjected to 
very heavy current drains during starting. The 
boat's engine may not always be run long enough 
to replace the energy used during starting and 
during long periods of inactivity; it is natural 
for the boat's batteries to lose energy. There- 
fore, it is very common for boat batteries to 
require charging from the ship's general purpose 
battery chargers. 

SMALL BOAT ELECTRICAL 
SYSTEMS 

The electrical systems found in small boats 
vary according to size and the intended purpose 
of the boat. In general, however, most boats 
possess electrical systems necessary for the 
operation of the boat's engine and navigational 
lights. 

The electrical systems associated with the 
boat's engine consist of starting system, battery 
charging system, and those electrically operated 
instruments necessary to properly monitor the 
engine's operation. These systems operate in a 



manner identical to the same type systems found 
in automobiles, except that, as stated before, 
most small boat electrical systems operate at 
24 VDC. 

When built properly, each craft has navi- 
gational lights provided by the manufacturer. The 
number of lights and their locations are deter- 
mined by the rules of the road governing the 
area where the boat is to be used principally 
(usually international rules of the road). 

Electrical equipment aboard small craft is 
subjected to unusually severe conditions 
humidity, salt spray, vibration, oil, and grease 
and will require a great deal of attention. 
Navigation lights, because of their infrequent 
use, are often overlooked during routine in- 
spections, thus creating embarrassing situations 
for electrical division personnel on more than 
one occasion. Naval Ships' Technical Manual, 
Chapter 583 (9820) contains more specific in- 
structions relating to small craft electrical 
equipment, including navigation lights and safety 
precautions. 

ELECTRICAL FORKLIFT 
TRUCKS 

Electrical forklift trucks (fig. 7-5) are used 
primarily for handling and transporting heavy 




Figure 7-5. Electric forklift truck. 
127 



5.58(77C)A 



SHIPBOARD ELECTRICAL SYSTEMS 





A - TYPE A RANGE 



B~ TYPE 60 OVEN 




C ~ TYPE 90 FRY KETTLE 



48.8.11 
Figure 7-6. Electric galley equipment. 

materials in confined areas where engine exhaust 
fumes cannot be tolerated. They are toeing used 
in ever increasing nurntoers atooard naval vessels 
of all types. 

Large capacity lead- acid storage batteries 
(36 or 24 volt) are used to furnish power for 
the drive and lifting mechanisms. These batteries 
are usually of such design that they are easily 
replaceable. This feature makes it possible 
to remove an exhausted battery and to replace 
it with a fully charged battery from the ship's 
battery locker, permitting continuous use of the 
forklift. 

The electrical components of the forklift 
include the battery, motors for the drive and 



lift mechanisms, and the control circuits requir 
for their operations. The control circuits for tl 
drive and lift motors usually consist of sol 
state devices which provide smooth posith 
control through an infinite number of varyir 
speeds. 

More detailed information regarding electri 
forklift trucks can be found in the manufacturer' 
technical manual for your particular equipmer 
or in Electrician's Mate 3 & 2, NAVEDTR 
10546. 



ELECTRIC GALLEY 
EQUIPMENT 

Electric galley equipment comprises the heav 
duty cooking and baking equipment installec 
aboard naval vessels and consists essentiall] 
of ranges, griddles, deep fat fryers, roasting 
ovens, and baking ovens (fig. 7-6). This equipment 
is supplemented by electric pantry equipment, 
which includes coffee urns, coffeemakers, grid- 
dles, hotplates, and toasters. The number and 
capacity of the units in a galley installation 
depends on the size and type of ship. Galley 
equipment is normally designed for operatior 
on 115-volt or 440-volt, 3-phase, 60-hertz, a.c. 
power. 



RANGES 

Electric galley ranges are provided in type 
A (36-inch), type B (20-inch), and type C (30-inch). 
The ranges consist of a range-top section and an 
oven section assembled as a single unit and a 
separate switchbox designed for overhead or 
bulkhead mounting. A type A range (fig. 7-6A) 
has three 6 -kilowatt surface units and an oven 
section with two 3-kilowatt enclosed heating units. 

OVENS 

A type 60 roasting oven (fig. 7-6B) consists 
of separate ovens, each of which is thermally 
insulated and operated independently of the 
others. The roasting ovens are provided in either 
two or three sections mounted one above the other. 
Each oven has a separately mounted switchbox 
which contains the fuses, contactors, and two 
or three heat switches, one for each section. 



128 



Chapter 7 AUXILIARY SHIPBOARD EQUIPMENT 



The type number of the oven denotes the capacity 
in pounds of raw meat per section. 

The type 12 and type 18 baking ovens are 
sectional type ovens with each section con- 
stituting a separate oven, thermally insulated 
and operated independently of the other sections. 
Each section of the type 12 or type 18 oven has 
a capacity of six standard five-loaf bread pans. 
The type 12 oven consists of two sections mounted 
one above the other. The type number denotes 
the total bread pan capacity of the oven. 

DEEP FAT FRYERS 

Electric deep fat fryers are normally provided 
in the type 23, type 45, and type 90 sizes. Each 
has enclosed electrical heating units rated at 
5 kilowatts, 10 kilowatts, and 18 kilowatts, 
respectively. A type 90 deep fat fryer is shown 
in figure 7-6C. 

The heating units are immersed directly in 
the fat to ensure maximum efficiency. The fryer 
is equipped with an adjustable automatic tem- 
perature control to maintain the fat at the desired 
temperature. The thermostat control, located 
on a panel at the front of the fryer, is provided 
with an OFF position and the adjustable tem- 
perature range of 250 to 400 F is displayed in 
gradations on the control knob. The thermostat 
operates contactors which, in turn, control the 
circuits to the heating units. 

A compartment located inside the fryer con- 
tains the contactors, thermostat, heating unit 
terminals, line terminal block, fuses, and line 
switch. The compartment is equipped with a 
removable panel for easy access to the control 
devices. 

Because of the fire hazards associated with 
deep fat fryers, they have been equipped with 
several safety devices. One of these safety 
devices consists of a circuit breaker located 
remotely from the deep fat fryer. The circuit 
"breaker permits manual interruption of power to 
the deep fat fryer in case of fire or any other 
emergency. Also associated with the remote 
circuit breaker is a high limit thermostat located 
inside the deep fat fryer. If the main thermostat 
in the fryer fails, permitting the oil temperature 
to exceed 460 F, contacts in the high limit 
thermostat close and cause the remote circuit 
breaker to open automatically and interrupt power 
to the deep fat fryer. 



ELECTRIC GALLEY 
EQUIPMENT MAINTENANCE 

Some of the more common problems en- 
countered with galley equipment are a result 
of the environment, cooking grease, oils, and 
high temperatures in which they operate. 

One relatively common problem is corroded 
connections due to prolonged exposure to heat and 
cooking oils. Another commonproblem associated 
with galley equipment is grounds which are 
usually caused by carelessness on the part of 
those who are responsible for the cleanness of 
the equipment. Spilled water on electrical contacts 
and damaged electrical insulation are not un- 
common occurrences. 



LAUNDRY EQUIPMENT 

Laundry equipment aboard ship is comprised 
of washers, extractors, and dryers. They may be 
installed separately or in combinations. This 
equipment operates primarily on 3-phase, 440 
VAC, 60-hertz power. The fully automatic 
washer-extractor with a card-o-matic program- 
mer is a representative piece of equipment. 



WASHER-EXTRACTOR 

The cylinder of the washer-extractor (fig. 7-7) 
has a 100 -pound dry weight capacity. A three- 
motor system drives the cylinder through its 
various wash/extract cycles by means of V-belts f 
speed reducers, and an air-operated clutch. Elec- 
tric solenoids control the supply of air for 
operating the clutch, brake, drain and steam 
valves, and detergent dispenser. Water level 
is controlled by three pressure-operated level 
switches; the water temperature is controlled 
by three adjustable thermostats. 

Though designed to operate automatically 
(formula mode), the washer-extractor can operate 
in the manual mode or in a combination of the 
two modes. The sequence and duration of the 
operations in the formula mode are controlled 
by the card-o-matic programmer (fig. 7-8) which 
also adds detergents and bleaches as pro- 
grammed. In the manual mode, the machine 
operator controls the duration and sequence of 
the wash/ extract cycle by positioning switches 



129 



SHIPBOARD ELECTRICAL SYSTEMS 




10 



Legend: 



1. OPERATING CONTROLS 

2. REMOVABLE SIDE PANEL 

3. DOOR BUMPER 

4. LIFTING BAR 

5. DATA PLATE 

6. SUPPLY HOPPER 

7. DRAIN VALVE AIR CYLINDER 



10 



8. WATER LEVEL BELLS 

9. DRAIN VALVE 

10. BASE PLATE 

11. SIGHT GLASS 

12. FRONT PANEL 

13. TUB DOOR LATCH 



Figure 7-7. -Front right view, Class 2258 Cascadex Washer- Extractor. 



77, 



as desired. Detergents and bleaches are added 
as desired by manual operations. 

Card-O-Matic 
Programmer 

The card-o-matic programmer controls every 
operation of the washer-extractor when it is 
operated in the automatic or formula mode. The 
operator selects the proper formula card accord- 

Sm^ the ^u f Washin S to be done - The 
formula card, which is inserted into the card 



reader portion of the card-o-matic programir 
determines the wash time, water temperati 
sequence of adding detergents, etc., during 
entire operation. Incorrect programming of 
formula card may cause the motor to s 



LAUNDRY EQUIPMENT 
SAFETY AND MAINTENANCE 

As a rule, present day laundry equipme 
complex in nature. This equipment is vit* 



JDV^J uiJriviJDiM j. 



20 



19 




16 



1. RUN INDICATOR 

2. STOP INDICATOR 

3. FORMULA CARD WINDOW 

4. SIGNAL INDICATOR 

5. SIGNAL SWITCH 

6. LEVEL SWITCH 

7. MASTER SWITCH 

8. SAFE ON SWITCH 

9. STOP INCH PUSHBUTTON 

10. INTERIOR LAMP (NOT SHOWN) 



11. THERMOMETER 

12. INCH START SWITCH 

13. STEAM SWITCH 

14. EXTRACT SWITCH 

15. CARD ADVANCE WHEEL 

16. DISCONNECT SWITCH 

17. OVERLOAD RESET BUTTON 

18. COLD WATER SWITCH 

19. HOT WATER SWITCH 

20. DRAIN VALVE SWITCH 



77.330 



Figure 7-8. Location of operating controls and indicators. 



the health and morale of the crew and should 
fee maintained to provide the best possible service. 
Most laundry equipment is equipped with a 
number of safety devices. If disabled, these 
safety devices can result, and have resulted, 
in shipboard fires, damage to equipment, damage 
to clothing, and in many cases personnel injuries, 
Special attention should be given these safety 
devices during preventive and corrective main- 
tenance with extra special attention being given 
those devices designed to protect operator per- 
sonnel. 



FIN STABILIZER SYSTEMS 

The fin stabilizer system is installed on 
FF's and FFG's to counteract the rolling motion 
of the vessel which results from wave motion 
and high speed maneuvers. The fin stabilizer 
systems installed on these ships are active, 
which means that some form of energy is supplied 
to move the fins. Though they are manufactured 
by different companies, we shall describe only 
the system designed by Sperry Rand since it is 
considered a representative system. This system 



131 



SHIPBOARD ELECTRICAL SYSTEMS 



provides a high degree of ship stability and 
enhances ship performance. 

GENERAL DESCRIPTION 

The main components of the ship stabilizing 
system are two machinery units, a control con- 
sole, and two motor controllers (fig. 7-9). 

Each machinery unit consists of a fin and 
fin-actuating machinery and is designed to be 
welded to the ship's hull. 

The two main hydraulic pump units are 
shock-mounted on the forward sides of the 
machinery units. Each pump unit consists of a 
variable delivery pump, a 50-hp electric-drive 
motor, and accessories. 

All roll measuring devices and equipment 
for computing the required stabilizing actions 
are housed within the control console. Its control 
panel contains the control devices and indicators 
for monitoring the fin stabilizer system operation. 



PRINCIPLES OF 
OPERATION 

Wave action, which causes the ship to roll, 
can be counteracted by applying righting or 
stabilizing moments to the ship in the direction 
opposite that of the disturbing wave action. One 
method of producing the moments is by means 
of two underwater fins. The capacity of these 
fins to stabilize a ship depends on the speed of 




140.183 
Figure 7-9. Typical fin stabilizer installation. 



the vessel, size of the fins, and the manner] 
which they are controlled. 

The fin stabilizer system, as shown in figu: 
7-10, consists of the control system, which con 
putes and orders the proper stabilizing momei 
and the machinery units, which develop t 
ordered stabilizing moment. 

The roll sensors measure the rolling act- 
caused by the disturbing wave action and ti 
supply data to develop the required staMliz 
moments. The computer servo unit orders the 
servo to tilt the fin, creating a fin lift or fo 
resulting from the combination of the fin 
and ship's movement. A stabilizing mom 
(or antiroll torque) results from the actior 
this force on the lever arm between the : 
and the ship's center of roll. 

The equality in fin forces, or lifts, is assi 
by equality of the ordered lift signals f 
the computer servo unit and by measurer 
of the actual lift exerted by each fin. The ord< 
lift signal and the actual lift signal are c 
pared in the positioning servos; any differ* 
in them is used to change the fin angle i 
actual lift is equal to ordered lift. 



FIN STABILIZING 

SYSTEM MAINTENANCE 

Fin stabilizer maintenance personnel 
strongly encouraged to refer to the mam 
turer's technical manual throughout cor re 
maintenance actions. Use of the technical m 
will greatly aid in troubleshooting and rep a 
this equipment, as is true with all other equipi 



STEERING SYSTEMS 

The steering system is considered one 
most vital auxiliaries since its operati 
necessary to maintain directional control 
vessel. Because of the vital role steering sy 
play, ships are usually provided with s 
different methods of direction control, 
method is made to operate as independent 
possible of the others. Several different 
supplies are provided to the steering s^ 
and several means of controlling the st< 
systems are provided on each ship. 



CONTROL SYSTEM 



ROLL 
SENSORS 




COMPUTER 
SERVO 
UNIT 





ACTUAL i PORT STABILIZER 




ORDERED 
STABILIZING 
MOMENT 
(ORDERED LIFT) 



POSITIONING 
SERVO 


\ 
\ 






HYDRAULIC 
SERVO 


--* 


Fl 




ACTUAL 




T 




1 




LIFT |_STARBOARD STABILIZE! 







[ER^ J 



SHIP'S ROLL MOTION 



Figure 7-10. Block diagram of fin stabilizer system. 



140,184 



STEERING GEAR 

The majority of steering gear installations 
in new construction naval vessels are of the 
electrohydraulic type. A typical electrohydraulic 
steering system is illustrated in figure 7-11. 
The electrohydraulic steering gear consists es- 
sentially of (1) a ram unit and (2) a power unit* 

Ram Unit 

The ram unit is mounted athwartship and 
consists of a single ram that operates in opposed 
cylinders. The ram is connected by links to the 
tillers of the twin rudders and is moved by the 
oil pressure built up in either of the cylinders, 
the oil from the opposite cylinder returning to 
the suction side of the pump. 

A rack is attached to the ram and engages 
two gears (followup pinions), the rotation of 
which is transmitted to the respective differential 
control boxes through the followup shaft. 

Power Unit 

The power unit consists of two independent 
pumping systems, which include two motor-driven 



pumps, two transfer valves with operating gear, 
relief valves, two differential control boxes, and 
two " trick" wheels mounted on a bedplate, which 
also serves as the top of an oil reservoir. Steer- 
ing power is derived from either pumping system 
acting alone. The power unit not in use serves 
as a standby unit in case of emergency. 

The two pumps (port and starboard) are 
identical in size and design, and are of the 
variable delivery axial piston type. Each pump 
is driven by a 440 -volt, 3-phase, 60-hertz in- 
duction motor through a flexible coupling. 

The pumps of the power unit are connected 
to the ram cylinders by a high-pressure piping 
system. The two transfer valves are interposed 
in this piping, and their positions determine 
which pump is connected to the cylinders in the 
ram unit. A hand lever and mechanical leakage 
(not shown) is connected to the two transfer 
valves in such a way that, by positioning the 
lever, both of the transfer valves are operated 
simultaneously. The hand lever is usually located 
between the trick wheels and it has three positive 
detent positions. The detented positions are 
marked P, N, and S which denote port pump 
connected to the ram, neutral (neither pump 
connected to the ram) and starboard pump con- 
nected to the ram, respectively. Usually, the 



133 



SHIPBOARD ELECTRICAL SYSTEMS 




<M 
00 



oJ 

a, 



1 



3 

?-H 

1 

1 

0) 



s 
a 



I 



Qjn.JLjrjDV-Att.x\.L/ 



land lever is also connected to remote motor- 
starting switches, permitting the operator to 
connect the selected pump to the ram and start 
the pump drive motor in one quick operation. 
This arrangement is most beneficial in the 
event of failure of the operating unit because 
it permits steering power to be shifted to the 
standby unit with one swift motion. 

The mechanical differential control box serves 
to correlate the mechanical signals from the 



followup shaft (which represents the rudder 
position) and the trick wheel, or the remote 
steering system (which represents the desired 
rudder position). If the desired and actual mech- 
anical signals are the same, the mechanical 
output from the differential control box will 
be zero. If the two signals are not in corre- 
spondence, the differential control box will pro- 
duce a mechanical output. The mechanical output is 
used to control the pump and, therefore, the 



SHIP'S 
STEERING WHEEL 

(HELM) 
SH/P'S CONTROL ( 




"1 

REMOTE 
STEERING 
CONTROL 
SYNCHRO 1 
TRANSMITTER 




PILOT HOUSE 


REMOTE STEERING 


~\ 

l 
I 




L . 


" / 

! */o 


~1 CONTROL CABLE 
SELECTOR SWITCH 




<jr o ^ j 

! L PORT OFF STBD. j 


- 


PORT 
REMOTE 
STEERING 
CONTROL 
CABLE 


STBOL 
REMOTE 
STEERING 
CONTROL 
CABLE 


L_ 




WNSOLE 




J 
















REMOTE 
STEERING 
SYNCHRO 
RECEIVER 
SELECTOR 
SWITCH 


STEERING GEAR MACHINERY 


ROOM 
















| PORT OFF STBD. 

...._._ 1 *A .** ^^ 1 


, 

| I 

1 n c 


k 

FT SI 


' 1 
1 

r> 1 


i \ j 

\ REMOTE STEERING 
1 \ (CONTROL CABLE 
1 [ 'SELECTOR SWITCH 




1 
|_ PORT 


P 

reo. J 
























\ 
PC 






1 

6 


1 
If \ 




\ 
1 

1 
1 

1 
1 










i ) 

REMOTE STEERING 
CONTROL STBD. 
SYNCHRO RECEIVER 

\_STBD. STEERING 6 




DIFFERENTIA! REMOTE STEERING 
CONTROL BOX CONTROL PORT 
CONTROL BOX SYNCHRO RECEIVER 

")RT STEERING GEAR UNIT 


DIFFERENTIAL 
CONTROL BOX 

'EAR UNIT 



27.393 



Figure 7-12. Remote steering control system. 

135 



SHIPBOARD ELECTRICAL SYSTEMS 



direction of hydraulic oil flow and pressure to 
the rams. Oil pressure from the pump causes the 
ram to move, which repositions the followup 
shaft, and movement continues in the desired 
direction until the differential control Tbox output 
equals zero. 



REMOTE STEERING 
CONTROL SYSTEM 

The remote steering control system provides 
control from the pilothouse for normal steering. 
Refer to figure 7-12. Movement of the pilot- 
house steering wheel rotates a synchro trans- 
mitter which is electrically connected to either 
of the synchro receivers located in the electro- 
hydraulic steering control mechanisms. Two 
sets of cables are installed between the trans- 
mitter and receiver synchros. To provide maxi- 
mum protection from Tbattle damage, one set is 
installed on the port side of the ship, and the 
other is installed on the starboard side of the 



ship. A selector switch is installed in the pil( 
house and in the steering gear room to pen 
selection of the control signal on either the pi 
or the starboard cable. These two switcl 
must be set to select the same cable dur 
operation. A third selector switch, install 
in the steering gear room routes the steer 
control signal to either the port or starbo 
synchro receivers located in the steering g 
unit to be used. This switch should be in 
OFF position when the trick wheel is to 
used. As shown in figure 7-12, the switc 
are aligned so that the port cable and 
starboard synchro receiver are selected, 
actual operation, any combination may be ui 
During remote control operation, the syncl 
transmitter in the pilothouse drives the selei 
synchro receiver. The receiver synchro meet 
ically drives the input shaft of the differei 
unit which controls the pump unit. The t 
wheel may be used to provide a mechar 
input to the differential control unit when i 
engaged. The trick wheel and synchro rece 
inputs are mechanically the same. 



136 



CHAPTER 8 

ALARM AND WARNING SYSTEMS 



Although they often constitute little more than 
a power source, a switch and a signaling 
device, the alarm and warning systems of the 
various Interior Communications systems are ex- 
tremely vital to any ship's operation,. Although 
simple in design and principles of operation, 
the importance of the alarm and warning systems 
cannot be overemphasized. They warn watch- 
standers of conditions that are dangerous to 
personnel or of conditions that could result in 
equipment damage if the equipment is allowed 
to operate under those conditions for an extended 
period* 

Over the years an attitude of indifference 
towards the alarm and warning systems has 
prevailed to the extent that, on any given naval 
unit, a number of these systems could be in- 
operable with little or no effort being expended 
to correct the problems. As a rule, the alarm 
and warning systems in the engineering spaces 
are the most seriously degradedo This may be 
attributed to three major reasons: 

1 These systems are subjected to extreme 
humidity and temperatures. 

2, The likelihood of physical damage to the 
systems is much greater because heavy equipment 
is rigged into and out of the spaces. 

3. The maintenance and testing of the alarm 
and warning systems usually require the efforts 
of individuals from at least two separate divisions. 

Effective coordination of the efforts of two 
or three divisions is difficult. Personnel do 
not arrive on station at the appointed time, 
therefore, man-hours are lost and disinterest 
grows. Those people who have no time to waste 
hesitate to assign their men to these details. 
The situation can continue to deteriorate to the 
point that efforts cease. 



As an officer in the Engineering Department 
you should ensure that each of the alarm and 
warning systems functions entirely as it was 
designed to do, and that every effort is made 
to coordinate the testing of all the components 
within the alarm system by simulating the con- 
ditions which the alarm is intended to detect. 

A listing of some of the alarm and warning 
system s with their circuit designations and classi- 
fications is contained in table 8-1. The principal 
components of alarm and warning systems are 
switches or contact makers, relays, thermostats, 
and audible and visual signals. 



SWITCHES 

Switches used with alarm and warning systems 
include m anual lever-operated switches, pressure 
and thermostatic switches, mechanical switches, 
and water switches. Relays are used to open and 
close circuits which may operate indicating 
lights, annuciators and/or audible signals. 



LEVER-OPERATED SWITCH 

Many types of lever-operated switches (fig. 
8-1) are used in Navy alarm and warning systems 
to complete electrical circuits to various types 
of audible and visual alarm signals. Two types of 
standard switches are available. One type has a 
spring return mechanism, and the other type 
has a positive detent mechanism. The type of 
switch used depends on the circuit in which 
it is installed. 

Special switches are used where the standard 
switches cannot be used. For example, the 
diving alarm switch on the submarine bridge must 
be pressure proof. For submarine service, a 
distinctive shape is used for the operating lever 
knob or heads of alarm switches in conning 



137 



SHIPBOARD ELECTRICAL SYSTEMS 



Table 8-1. Alarm and Warning Systems 



Circuit 


System 


Importance 


Readiness Class 


BZ 


Brig cell door alarm and lock operating 


NV 


4 




BW 


Catapult Bridle Arresterman safety Ind. 


NV 


1 




CX 


Bacteriological Lab. & Pharmacy Comb. Refer 
Failure 


NV 


1 




DL 


Secure communications space door position 
alarm 


NV 


1 




DW 


Wrong direction alarm 


V 


2 




EA 


Reactor compartment or fireroom emergency 
alarm 


NV 


1 




IEC 


Lubricating oil low pressure alarm- 
propulsion machinery 


sv 


2 




2EC 


Lubricating oil low pressure alarm- 
auxiliary machinery 


sv 


1 




1ED 


Generator high temperature alarm 


sv 


1 




2ED 


Oxygen-nitrogen generator plant low tem- 
perature alarm 


NV 


1 




EF 


Generator bearing high temperature alarm 


SV 


1 




EG 


Propeller pitch control, hydraulic oil system 
low pressure alarm 


SV 


2 




EH 


Gas turbine exhaust high temperature 
alarm 


sv 


1 
2 


(aux. machinery 
(prop, machiner; 


EJ 


Feed pressure alarm 


sv 


1 




1EK 


Pneumatic control air pressure alarm 


NV 


2 




3EK 


Catapult steam cutoff and alarm 


NV 


2 




XEL 


Radar cooling lines temperature and flow alarm 


NV 


1 




EP 


Gas turbine lubricating oil high temperature 
alarm 


SV 


1 
2 


(aux. machinery 
(prop, machiner 


1EQ 


Desuperheater high temperature alarm 


SV 


1 




2EQ 


Catapult steam trough high temperature 
alarm 


sv 


2 





27.3 



138 



njurvruvi .CVLVU wrirxiNiiNvjr o ID1 JDlVIo 



Table 8-1. Alarm and Warning Systems continued 



Circuit 


System 


Importance 


Readiness Class 


3ES 


Reactor fill alarm 


V 


1 


ET 


Boiler temperature alarm 


NV 


1 


EV 


Toxic vapor detector alarm 


sv 


1 


1EW 


Propulsion engines circulating water high 
temperature 


sv 


1 


2EW 


Auxiliary machinery circulating water high 
temperature 


sv 


1 


EZ 


Condenser vacuum alarm 


sv 


2 


F 


High temperature alarm 


sv 


1 


4F 


Combustion gas and smoke detector 


sv 


1 


9F 


High temperature alarm system-ASROC 
launcher 


sv 


1 


11F 


FBM storage area temperature and humidity 
alarm 


sv 


1 


12F 


Gyro ovens temperature and power failure 
alarm 


sv 


1 


FD 


Flooding alarm 


NV 


1 


FH 


Sprinkling alarm 


sv 


1 


FL 


Flight Deck Landing Area Status Light 
Signal system 


NV 


2 


FR 


Carbon dioxide release alarm 


NV 


1 


FS 


Flight Deck Readylight Signal system 


NV 


2 


FZ 


Security alarm (CLASSIFIED) 


V 


1 


4FZ 


Torpedeo alarm (CLASSIFIED) 


V 


1 


HF 


Air flow indicator and alarm 


sv 


1 


LB 


Steering Emergency Signal system 


NV 


2 


LS 


Submersible steering gear alarm 


SV 


2 



27.352.1 



139 



SHIPBOARD ELECTRICAL SYSTEMS 



Table 8-1. Alarm and Warning Systems continued 



Circuit 


System 


Importance 


Readiness Class 


MG 


Gas turbine overspeed alarm 


SV 


1 
2 


(aux. machinery) 
(prop, machinery) 


NE 


Nuclear facilities air particle detector alarm 


NV 


1 




NH 


Navigation Horn Operating System 


NV 


2 




QA 


Air lock warning 


NV 


1 




QD 


Air filter and flame arrester pressure differen- 
tial alarm, or gasoline compartment exhaust 
blower alarm 


V 


1 




QX 


Oxygen-nitrogen plant ventilation exhaust alarm 


SV 


1 




RA 


Turret emergency alarm 


NV 


1 




RD 


Safety observer warning 


NV 


2 




RW 


Rocket and torpedo warning 


SV 


3 




4SN 


Scavenging air blower high temperature alarm 


V 


2 




SP 


Shaft position alarm 


NV 


2 




TD 


Liquid level alarm 


NV 


1 




1TD 


Boiler water level alarm 


NV 


1 




2TD 


DeaeratLng feed tank water level alarm 


NV 


1 




5TD 


Reactor compartment bilge tank alarm 


SV 


1 




6TD 


Primary shield tank, expansion tank level alarm 


NV 


1 




7TD 


Reactor plant fresh water cooling expansion tank 
level alarm 


NV 


1 




8TD 


Reactor secondary shield tank level alarm 


NV 


1 




9TD 


Lubricating oil sump tank liquid level alarm 


SV 


1 




11TD 


Induction air sump alarm 


SV 


1 




12TD 


Diesel oil sea water compensating system tank 
liquid level alarm 


SV 


1 




14TD 


Auxiliary fresh water tank low level alarm 


NV 


1 





27.3 



rx.Lj.tt.ruvi 



WrllxlNliNljr d ID 1 JMVlD 



Table 8-1. Alarm and Warning Systems continued 



Circuit 


System 


Importance 


Readiness Class 


16TD 
17TD 


Pure water storage tank low level alarm 
Reserve feed tank alarm 


SV 

NV 


1 
1 


18TD 


Effluent tanks and contaminated laundry tank 
high level alarm 


V 


1 


19TD 


Sea water expansion tank low level alarm 


SV 


1 


20TD 


Gasoline drain tank high level alarm 


SV 


1 


21TD 


Moisture separater drain cooler high level alarm 


NV 


1 


24TD 


Reactor plant on board discharge tank level alarm 


V 


1 


25TD 


Crossover drains high level alarm 


SV 


1 


29TD 


Sonar dome fill tank low level alarm 


SV 


1 


30TD 


JP-5 fuel drain tank high level alarm 


SV 


2 


TW 


Train Warning system 


NV 


1 


W 


Whistle Operating System 


NV 


2 



Legend: 

V-Vital SV-Semivital NV-Nonvital. 

1 Continuously energized-supply switch color code yellow. 

2-Energized when preparing to get underway, while underway, and until the ship is secured- 
supply switch color code black. 

3 Energized during condition watches -supply switch color code red. 

4-Energized only when required-supply switch color code white. 

All electronic type alarm systems formerly designated as circuits CA, FC, FW, G, GD, GJ, GN, 
and GP are now classified as a portion of the respective announcing system with which they are 
associated* 



27.352.1 




140.4 

Figure 8-1. Lever -operated switch (manual 
contact maker). 



tower and control room (where illumination 
is low) to avoid confusion in operating the proper 
switcho A square- shaped knob is used for the diving 
alarm switch, a star-shaped head for the collision 
alarm switch, and a standard round head for 
general alarm 

Lever-operated switches are used in such 
systems as the fireroom emergency signal, 1 
general alarm, chemical- attack alarm, steering 
emergency signal, whistle operation, life buoy 
release, and flight-crash signal. 



PRESSURE SWITCH 

Pressure-operated switches (fig. 8-2) contain 
either a bellows or a diaphragm that works 
against an adjustable spring. The spring causes 
the contacts to close or open automatically when 



141 



SHIPBOARD ELECTRICAL SYSTEMS 




77.119(140) 
Figure 8-2 Pressure switch type IC/L. 



Thermostatic Switch Type IC/N I 

The type IC/N therm ostatic or temperature- j 
operated switches (fig. 8-3) are constructed 
similarly to the previously discussed pressure ( 
switches. Each switch contains a bellows whicl; 
works against an adjustable spring. The spring! 
causes the contacts to close or open automatically! 
when the operating temperature exceeds or fallsj 
below a specified value The motion of the! 
bellows is produced by a sealed~in liquid that ; 
expands with rising temperature. The sensitive 
element containing this liquid may be an integral 
part of the switch or it may be located in a 
remote space and connected to the switch by a 
capillary tube. 

The therm ostatic switch is available to sense 
a wide range of temperatures; each switch is 
adjustable to a specific temperature within its 
range. The therm ostatic switch physically re- 
sembles the pressure switch except that a sensi- 
tive element or capillary tube is connected when 
the pressure source would be connected to tin 
pressure switch* 

The IC/N temperature-operated switches ar 
used with the circulating-water high-temperatur 



the operating pressure falls below or exceeds 
a specified value. These switches are available 
to sense pressure changes in ranges of 0-15, 
15-20, 50-100 pounds, etc. Special switches are 
available which sense very high pressure or 
vacuums. The exact pressure at which the con- 
tacts close or open is adjustable, as long as 
the desired setting is within the range of the 
switch. 

Pressure-operated switches are used with 
the lubricating oil low-pressure alarm system, 
pneumatic control air pressure alarm system, 
and booster-feed pressure alarm system, as 
well as others. Pressure-operated switches are 
also used to control electrical circuits; for 
example, to start an electrically driven emergency 
lube oil pump when the pressure from the main 
pump falls below a specified value. 



THERMOSTATIC SWITCHES 




The Navy uses two basic types of therm ostatic 
switches for alarm circuits: type IC/N and 
mercury. 



77.1! 
Figure 8-3. Thermostatic-operated switch, Ty 

IC/N. 



142 



Chapter 8 ALARM AND WARNING SYSTEMS 




27.308 



Figure 8-4* Mercury thermostat,, 



alarm system, cruising- turbine exhaust alarm 
system, and generator- air high-temperature 
alarm system, as well as others. 

Mercury Thermostatic Switch 

The sensitive unit of the mercury thermostatic 
switch (fig. 8-4 and 8-5) is similar in construction 
to an ordinary mercury thermometer, except that 
three metal electrodes are inserted into the 
glass enclosure.. The electrodes complete contact 
with the mercury column as the height of the 
mercury increases in the glass tube. An increase 
in temperature results in the mercury's shorting 
out the upper and lower contacts which completes 
the electrical circuit; the middle contact is 
used in conjunction with the supervisory circuit 
which will be discussed later in this chapter. 

The thermostats are designed to close their 
contacts at temperatures of 105, 125, or 150F. 



LINE 




27.309 
Figure 8-5. Mercury thermostat sensitive unito 



143 



SHIPBOARD ELECTRICAL SYSTEMS 



Except for differences in temperature ratings, 
the thermostats are similar. A defective thermo- 
stat must be replaced with one that has the same 
temperature rating* Mercury thermostat switches 
are used in ship's fire alarm system circuit F. 

WATER SWITCH 

Water switches consist of a pair of contacts 
mounted on an insulated base within a cast 



fitting (fig, 8-6). The switch is mounted in the 
m agazine flooding system with a sprinkling control 
valve installed between the switch and the firt 
main. When the sprinkling control valve it 
opened, salt water floods the switch casting ani 
shorts out the contacts, thereby permitting i 
current flow of sufficient value to operate th< 
alarm. The resistor in figure 8-6 is used i 
conjunction with the supervisory circuit an 
will be discussed later in this chapter. 









SECTION B-B 

LEGEND 

(T) SPACER. (J) 1/8" STANDARD PIPE PLUG. 

(T) CONTACTS. (T) CLAMP. 

i\ "0" RING GASKETS. (7) RESISTOR, 7000 OHMS.5 WATT. 



SUGGESTED METHOD OF MOUNTING WATER SWITCH 

-SPRINKLING CONTROL VALVE 



INSTALL WATER SWITCH ON 

UNDERSIDE OF PIPING ON 

THE DRY SIDE OF THE 

SPRINKLING CONTROL VALVE 





\_ 



WET SIDE 



WATER SWITCH 



Figure 8-6. Water switch. 
144 



140. 



Chapter 8 ALARM AND WARNING SYSTEMS 



LIQUID-LEVEL 
FLOAT SWITCH 

The liquid-level float switch (fig* 8-7) is used 
in tank and bilge level alarm circuits,, T"ie switch 
assembly consists of a center column with a 
magnetically operated reed switch encapsulated 
inside it, A float, containing a magnet, surrounds 
the center column and is free to move up and 
down the column The movement of the float 
with its magnet causes the contacts of the reed 
switch to open or close. By mounting the switch 
assembly at a predetermined level in a tank or 
bilge, it can be made to give above or below 
normal liquid level indications. 

The liquid level float switch is used in the 
flooding alarm circuit FD, as well as others. 




MECHANICAL SWITCH 

Mechanical switches are employed to indicate 
the position of a component or to sound an alarm 
if the component is not in the proper position. 
These switches usually contain microswitches 
which are actuated by either a cam or a push- 
operated plunger. The push- action plunger mech- 
anism utilizes a straight line movement of the 
shaft to operate a microswitch. 

The cam-action switch consists of two micro- 
switches operated by two adjustable cams mounted 
on the rotor shaft (fig. 8-8.) The cam-action 
mechanism utilizes a rotary motion of the shaft 
to move cams, which in turn operate micro- 
switches. The points of operation of the micro- 
switches are varied by adjustment of the angular 
positions of the cams with respect to the shaft 
on which they are mounted. Mechanical switches 
are used in the secure communications space 
door position alarm (circuit DL); wrong direction 
alarm (circuit DW); airlock warning (circuit 
QA); as well as in other circuits. 

COMBUSTION GAS AND 
SMOKE DETECTOR 

The combustion gas and smoke detector (fig. 
8-9) is an electronic switch. The presence of 
smoke or combustion gases causes the internal 
resistance of the detector to decrease drastically, 
thereby allowing it to conduct a larger current 
in much the same way as the closing of the 
mechanical contacts of an ordinary switch. The 
detector contains small quantities of radium 
and, therefore, should be handled and disposed 



SHAFT 



.MICRO 
SWITCHES 



ADJUSTABLE 
CAMS 




Figure 8-7. Float switch. 



140.63X 



140.6 
Figure 8-8. Cam-action mechanical switch. 



145 



SHIPBOARD ELECTRICAL SYSTEMS 





Figure 8-10. Cowbell type IC/B354. 



27.2S 



27.310 

Figure 8-9 Combustion gas and smoke detector 
head* 



of in accordance with current directives for 
radioactive material. The combustion gas and 
smoke detector is used in the combustion gas and 
smoke detection .system 1C circuit 4F. 



AUDIBLE SIGNALS 

There are many types of audible signals in 
use aboard Navy ships The principal types of 
audible signals are bells, buzzers, horns, and 
sirens. Electronic signals are used for some 
applications on new construction ships, Ths 
type of signal used depends on the noise level 
at the location and on the kind of sound desired, 

BELLS AND BUZZERS 

Bells used with alarm and warning systems 
may be either aoC, or dc a operated, either 
watertight or watertight explosion proof con- 
struction, with either circular or cowbell-shaped 
gongs* 

Alternating current bells have any one of three 
types of gongs; circular 3-inch diameter, circular 
8-inch diameter, and the cowbell type (fig. 8-10). 



Direct current bells have any one of thre 
types of gongs: circular 2 1/2-inch diainete: 
circular 8-inch diameter (fig. 8-11), and cowbe! 
type. 

Buzzers are used only in relatively quit 
spaceSo Buzzer, type IC/Z1D4 (fig. 8-12), i 
d.c operated and has make and break contact 




Figure 8-11, IC/B2D4 bell. 



27,2i) 



Chapter 8 ALARM AND WARNING SYSTEMS 



Buzzer, type IC/Z1S4, is a.c. operated and has 
no contacts* 



HORNS \ND SIRENS 

Nonresonated horns utilize a diaphragm actu- 
ated by a vibrating armature to produce sound of 
the required intensity,, 

Resonated horns (fig. 8-13) also use dia- 
phragms and, in addition, have resonating pro- 
jectors to give the sound a distinctive frequency 
characteristic. The resonated horn is designed 
in a variety of types differing as to intensity, 
frequency, or power requirements. 

Motor-operated horns, or klaxons, utilize 
electric motors to actuate the sound-producing 
diaphragm So These horns are used in the diving 
alarm system aboard submarines, as well as 
in other circuits. Figure 8-14 is a cutaway view of 
a motor-operated horn. 




Figure 8-1 3 Resonated horn a 



27.300 





(\J BEARING, REAR OILITE 

(?) MOTOR HOUSING 

(3) MOTOR SUPPORT, REAR 

MOTOR SUPPORT, FRONT 

(?) FILTER 



(6) INSULATOR 

(7) RATCHET 

ANVIL 

() DIAPHRAGM 

(io) FRONT COVER ASS'Y 



Figure 8-12.--IC/Z1D4 buzzer. 



27.299 Figure 8-14.- 



27.300 

-Cutaway view of motor-operated 
horn. 



147 



SHIPBOARD ELECTRICAL SYSTEMS 



Sirens are used in very noisy spaces to sound 
urgent alarms. The sound is produced by an 
electric motor driving a multiblade rotor past 
a series of ports or hole sin the housing (fig, 8-15). 
The sound is made by the air as it is forced 
through the ports. The frequency of the sound 
depends on the number of ports, the number of 
rotor blades, and the speed of the motor. 

ELECTRONIC SIGNAL UNITS 

The type IC/E1D1 electronic signal unit (fig. 
8-16) is designed as a power failure alarm. The 
unit contains an electronic solid state oscillator 
which produces an audible signal upon loss of 
power to the bus that is being monitored by the 
alarm unit* 

The oscillator receives its power from a 
small nickel-cadmium battery which is maintained 
on a low charge when the monitored bus is 
energized. The unit will operate on 115 volts, 
d.c* or a.c. (60 Hz or 400 Hz), without modification. 



VISUAL SIGNALS 

Visual signals are used in a great many 
alarm and warning systems as an additional 
means of identifying the alarm being sounded. 
Audible and visual signals are of ten used together 
In noisy spaces audible signals are supplemented 
by visual signals, and in brightly lighted spaces 





Figure 8-1 5,-- Siren. 



27.301 



27.302 
Figure 8-16. Electronic signal unit type IC/E1D1, 



visual signals are supplemented by audible sig- 
nals. In many instruments the same audible device 
is used in combination with several visual indi- 
cators. The principal types of visual signals 
are lamp-type indicators and annunciators sucl 
as those utilized in alarm switchboards and panels, 

LAMP- TYPE INDICATORS 

Standard watertight, lamp- type indicators are 
designed as single-dial, 2-dial, (fig. 8-17) , 4-dial, 
or 6-dial units. Two lamps are connected io 
parallel and mounted behind each dial to provide 
protection against the loss of illumination ID 
case one lamp burns out* A colored-glass disk 
and sheet-brass target engraved with the alarm 
identification are illuminated from the rear tj 
the two lamps. Glass disks are furnished IE 
eight standard colors, dependent on the applica- 
tion. 

The power to the lamps is in parallel witt 
the audible signal. When the audible signal 
sounds, the lamps illuminate the colored glass 



148 



Chapter 8 ALARM AND WARNING SYSTEMS 




/#^ 




27.303.1 



Figure 8-17 Lamp type indicator. 



and brass target of the indicator and identify 
the alarm being soimdedo This type of indicator 
is used with various alarm system s 

ALARM ANNUCIATORS 

There are two basic types of alarm annun- 
ciators in general use. Each of these types 
supervises the circuit to which it is connected, 



providing alarm signals in the event of an alarm 
condition, and supervisory signals in the event 
of an open circuit between the indicator and the 
remote alarm sensor (switch). 

The alarm annunciator measures the current 
flow through the circuit that is connected to it 
and differentiates between a normal, an alarm, 
or an open circuit condition,, The circuit that 
is connected to the alarm annunciatox* has a 



149 



SHIPBOARD ELECTRICAL SYSTEMS 



resistor attached across the last switch in the 
line of that circuit, as shown in figure 8-18. 
This resistor, called the supervisory resistor, 
permits a limited amount of current to flow 
through the circuit when the switch is open. 
This limited amount of current flow represents 
the normal circuit condition. Less current flow 
through the circuit or an open circuit results 
in supervisory signals being produced; more 
current flow through the circuit as when the 
switch closes, results in alarm signals being 
produced. 

Alarm annunciators are used in conjunction 
with larger assemblies to form alarm switch- 
boards or switchpanels which may supervise 
from 2 to more than 50 individual alarm circuits. 

Two-Line Alarm Unit 

The two-line alarm unit (fig. 8-19) provides 
equipment for supervising two circuits. Each 
circuit has an alarm-target relay, a supervisory- 
target relay, and a test-cutout switch. The two- 
line unit has two alarm target relays mounted side 
by side at the rear near the bottom of the unit 



paneL Each alarm target relay has conti 
which operate external alarm signals and 
an indicator drum which projects a red ta: 
into the square opening in the face of the pi 
when the relay is operated. The two supervig 
target relays have contacts that operate exte: 
supervisory signals and have indicator dr\ 
that project a yellow target into the sqt 
openings in the face of the panel when the r< 
is restored. 

Under normal conditions the current flov 
through the supervisory resistor is suffic 
to operate the supervisory relay but not 
alarm relay. Therefore, neither the red all 
target nor the yellow supervisory target is vis 
in the openings in the front panel. 

The test-cutout switch is a three-posi 
switch. In the normal position the alarm indict 
monitors the remote switch for alarm or sup 
visory conditions. In the test position the sw 
simulates an alarm condition, and is used to 
the components internal to the alarm indie? 
and the external alarm signals. THE T] 
POSITION VERIFIES ONLY THAT THE ALA 



SUPERVISORY 
RESISTOR 



J ASWITCH 

f 1 


ALARM 
ANNUNICATOR 




MERCURY 
THERMOSTATS 

JL 





ALARM 
ANNUNICATOR 




SUPERVISORY 
RESISTOR 



Figure 8-18. Basic alarm circuit with supervisory resistor. 

150 



27.9 



Chapter 8 ALARM AND WARNING SYSTEMS 




SUPERVISORY 
RELAY and TARGET 



ALARM 

RELAY and TARGET 




/' 

TEST and 4vt 

CUTOUT SWITCH "" 



SIDE VIEW 



FRONT VIEW 



Figure 8-1 9 . Two-line alarm unit. 



27.304 



INDICATOR IS FUNCTIONING PROPERLY. IT 
DOES NOT VERIFY THAT THE REMOTE SEN- 
SORS WILL FUNCTION AS THEY WERE IN- 
TENDED. The cutoutpositionisusedto silence the 
external alarm or the supervisory audible signal. 

IC/M Alarm Module 

The IC/M alarm module performs the same 
function as the two-line alarm unit previously 
discussed. This unit is of more recent design 
than the two-line alarm unit, and it must be 
employed in an alarm switchboard which contains 
an audio generator. The audio generator produces 
audible signals for alarm and supervisory con- 
ditions. 

The alarm module (fig. 8-20) has a manual 
selector switch for placing the module in either 
NORMAL, STANDBY, CUTOUT, or TEST modes 
and has a divided, lighted display, either half 
of which can show a steady or a flashing red 
light or no light, as required. 



Under normal conditions, the upper lamp is 
"on steady," and the lower lamp is off (fig. 8-21). 
During an alarm condition, the upper lamp flashes 
and a wailing tone from the associated switchboard 
sounds. 

To acknowledge an alarm , the switch is 
shifted to STANDBY and the audible alarm is 
silenced while both the upper and lower lamps 
are "on steady." After the alarm condition is 
cleared, the lower lamp flashes while the upper 
lamp goes out. A pulsating tone from the associated 
switchboard informs the operator to return the 
switch to the NORMAL position. 

If the supervisory resistor on the circuit to 
the switch should open, the upper lamp goes 
out while the lower lamp is "on steady"; a pulsa- 
ting tone from the associated switchboard alarm 
sounds when the module is in the NORMAL mode. 
Then, the alarm is silenced by placing the mode 
selector switch to CUTOUT. In this position 
the lamps indicate the same as thev do for 
supervisory failure: top lamp out, lower lamp 
"on steady," no audible alarm. 



151 



SHIPBOARD ELECTRICAL SYSTEMS 




140.122 



Figure 8-20. IC/M alarm module. 



Placing the mode selector switch in the TEST 
position simulates an alarm condition. For this 
position the upper lamp flashes while the lower 
lamp is out, A wailing tone alarm sounds just 
as it does for an alarm condition in the NORMAL 
mode. 



ALARM PANELS AND 
SWITCHBOARDS 

Alarm panels and switchboards are used in 
conjunction with a majority of the alarm systems 
which monitor equipment or spaces, such as the 
low-lubricating oil pressure alarm, flooding and 
fire alarm systems. 



ALARM SWITCHBOARDS 

There are two basic types of alarm switch- 
boards. While both perform the same functions, 
one uses the two-line alarm units, and the other 
uses the IC/M alarm module. Alarm switchboards 
are usually installed in spaces that are con- 
tinuously monitored, both in port and underway, 
Switchboards supervise a large number of sensor 
circuits which are installed in numerous locations 
throughout the ship, such as the mercury thermo- 
stats employed in 1C circuit F. 



Two-Line Unit Alarm 
Switchboard 

The two-line unit alarm switchboard is shown 
in figure 8-22, The upper section comprises the 
alarm panel which contains an alarm bell, a 
test light, a trouble buzzer, two ground-detector 
lamps, a power available lamp, a trouble test 
lamp, and a test key. An extension signal relay, 
capable of operating up to four alarm bells 
located at remote stations on the ship, is mounted 
at the rear of the alarm panel. As long as the 
power supply to the switchboard is maintained, 
the power available light at the center of the 
panel glows. 

The lower section of the two-line unit alarm 
system switchboard (fig. 8-22) may consist of as 
many 10-line or 20-line panels as are necessary to 
accommodate the total number of high- 
temperature circuit F , or water- sprinkling circuit 
FH stations aboard the ship. Six 10-line panels 
capable of accommodating 60 lines are shown in 
figure 8-22. The switchboard apparatus for each 
two lines is mounted together in a removable 
alarm unit as shown in figure 8-19, Five of these 
2-line units are arranged to make up a 10-line 
panel, A nameplate located above the cutout 
test key identifies the compartment or the spaces 
served by that line. 



ALARM PANELS 

Alarm panels are produced in two standard 
sizes to supervise two or four remote sensors. 
The alarm panel enclosure houses one or two 
of the standard two-line alarm units. Alarm panels 
are usually .mounted adjacent to the equipment 
which is monitored by the alarm sensors. 



Type IC/SM Alarm 
Switchboard 

The type IC/SM supervisory alarm switch- 
board (fig. 8-23) provides centralized monitoring 
of remotely located sensors. The features of the 
type IC/M alarm module, as previously explained, 
have been incorporated into this alarm switch- 
board,, 



152 



Chapter 8 ALARM AND WARNING SYSTEMS 



NORMAL 



NORMAL ALARM 
OR TEST 



C0MPT, 




STAND-BY ALARM 



OOMFT. 



WAILING 



STANDBY 
ALARMCLEARED 



CUTOUT 



COMPT. 
1-126-A 




SUPERVISORY 
FAILURE 



COMPT. 
M26-A 



COMPT. 
1-126-A 



PULSATING 




~- PULSATING 



Figure 8-21. 1C /SM visual displays and audible outputs. 



140.123 



The upper section of the switchboard houses a 
speaker, signal generator, audible signal silence 
control switch, lamp dimmer, power supplies, 
buses, and ground detector lamps. The audible 
signal silence control switch is utilized to disable 
the audible alarm feature, while the visual alarm 



system remains fully operational. The audible 
signal silence indicator alerts personnel when the 
audible signal is not operational,, 

The lamp dimmer affects all the module indi- 
cating lights except the alarm condition lights 
which continue to flash at a full brilliance. 



SHIPBOARD ELECTRICAL SYSTEMS 



ALARM TEST KEY 



TEST LIGHT 



ALARM BELL 



ALARM TEST LAMP 



POSITIVE GROUND 
DETECTOR LAMP 



BLOWN FUSE 

INDICATOR 

FOR EXTENSION 

SIGNAL CIRCUITS 




FROUBLE BUZZER 



TROUBLE 
TEST LAMP 



NEGATIVE GROUND 
DETECTOR LAMP 



POWER AVAILABLE 
LAMP 



27.307 



Figure 8- 22* Two-line unit alarm switchboard. 



154 



Chapter 8 ALARM AND WARNING SYSTEMS 



GROUND 

DETECTION 

LAMPS (fa-) 

AUDIBLE 

SIGNAL 

SILENCE 

CONTROL 



LAMP 
DIMMER 



AUDIBLE 
SPEAKER 




AUDIBLE 
SIGNAL 
SILENCE 
INDICATOR 



MAIN 

POWER 

FUSE 



INDIVIDUAL 
DISPLAY 
MODULES 
(10 per Line) 



Figure 8-23, IC/SM switchboard showing 10 active modules in place. 



140,121 



ALARM SYSTEMS plus the different types of switches, indicating 

devices, and signals, employed in each circuit 
make it unique to other circuits. Several of the 

As previously stated, most alarm systems various alarm systems will be discussed in this 
consist of a switch, power supply, and some section. Diagrams are included to aid you in 
type of indicating device, whether it be audible, understanding how the various components we have 
visual, or a combination of the two. The par- described in this chapter are employed to form a 
ticular equipment or component being monitored complete alarm system fl 



155 



SHIPBOARD ELECTRICAL SYSTEMS 



HIGH-TEMPERATURE 
ALARM SYSTEM 

The high-temperature alarm system (circuit 
F) is used aboard ship to detect and warn of fires 
or overheated conditions in designated com- 
partments and spaces. Usually this circuit em- 
ploys the mercury-type thermostats and one of 
the two types of alarm switchboards (figo 8-24) 
The thermostats are installed on the overhead 
and require a free circulation of air a 



The 125 and 150 thermostats are normally 
installed in storerooms, paint lockers, and similar 
spaces that house combustible stores. The 105 
F thermostat is normally installed in magazines. 

As many thermostats as are needed for the 
prompt detection of a fire can beconnectedto any 
one line. If more than one thermostat is used in a 
compartment, only one supervisory resistor is 
required. When any one of the thermostats in the 
group is overheated, the alarm operates,, These 



PAINT LOCKER 



MT.51 MAGAZINE 




POWER FROM 

MAINIC 

SWITCHBOARD 



27.379 



Figure 8- 24 ~- High- temperature alarm system, 
156 



Chapter 8 ALARM AND WARNING SYSTEMS 



thermostats, or groups of thermostats, are con- 
nected to the alarm switchboard by multiconductor 
cable* Each circuit on the alarm switchboard is 
marked to designate one compartment, and the 
thermostat, or group of thermostats, installed 
in each compartment is connected to the circuit 
marked for that compartment. 



SPRINKLING ALARM 

SYSTEM 

The sprinkling alarm system, circuit FH, is 
basically the same as the high-temperature alarm 
system except that water switches (fig. 8-6) are 
used instead of mercury thermostats. 



COMBUSTION GAS AND 
SMOKE DETECTOR SYSTEM 

The combustion gas and smoke detector system 
(circuit 4F) detects and warns of the presence of 
combustion gases or smoke. The alarm circuits 
operate similar to the high-temperature fire 
alarm circuits, A combustion gas and smoke 
detector (fig 8-9) is used as the sensing device* 



CIRCULATING-WATER, 
HIGH-TEMPERATURE 
ALARM SYSTEM 

The circulating-w a t e r , h i g h- temperature 
alarm system, circuits 1EW and 2EW, auto- 
matically indicates when the circulating-water 
temperature of the main propulsion diesel engines 
or the large auxiliary diesel engines rises above 
the predetermined maximum limit. When the 
system is used for the main engines, the circuit 
is designated 1EW; when the system is used 
for auxiliary engines, the circuit is designated 
2EW. The circulating- water, high-temperature 
alarm system is usually combined with the 
lubricating-oil, low-pressure alarm system (fig* 
8-25) and consists of temperature-operated 
switches (fig 8-3) located in the circulating 
water lines of the engines* A rise in temperature 
above a predetermined point causes the alarm 
to sound. 



GENERATOR AIR HIGH- 
TEMPERATURE ALARM AND 
THE GENERATOR BEARING HIGH- 
TEMPERATURE ALARM SYSTEMS 



LUBRICATING-OIL, LOW- 
PRESSURE ALARM SYSTEM 



The purpose of the lubricating-oil, low- 
pressure alarm system, circuits 1EC and2EC,is 
to sound an alarm whenever the pressure in the 
lubricating-oil supply line to the main engine 
and reduction gear, or to the turbine- driven or 
diesel-driven generators, and other auxiliary 
machinery falls below a predetermined minimum 
limit. When the system is used for the main 
engines, the circuit is designated 1EC; when 
the system is used for either turbine-driven or 
diesel-driven generators and other auxiliaries, 
the circuit is designated 2EC. Both circuits 
are energized from individual switches on the 
local 1C switchboard which is located in the 
appropriate engineroom,, 

An EC circuit includes one or more pressure 
type switches (fig. 8-2) installed in the lubricating- 
oil lines of the associated equipment. The alarm 
panel of the lubricating-oil, low-pressure alarm is 
located near the operating control board of the 
machinery on which the pressure switch is 
installed. 



The generator air high-temperature alarm 
system, circuit 1ED, provides a means of indi- 
cating high temperature of the cooling air exhaust 
of generator sets rated at 500 kW and above. 
The system consists of type IC/N thermostatic 
switches, which energize visual and audible 
signals whenever the temperature of the circu- 
lating air rises above a predetermined limit. 

The generator bearing high- temperature 
alarm system, circuit EF, provides a means 
of indicating high temperatures in the bearings 
of generator sets of 200 kW and above. Thermo- 
static switches energize visual and audible signals 
when a bearing temperature rises above a pre- 
determined limit. 



SYSTEMS MAINTENANCE 



As a rule the principles of operation of alarm 
and warning systems are simple. However, be- 
cause of the large number of systems installed 
on most ships, this equipment will require a good 
deal of attention from maintenance personnel. 



157 



SHIPBOARD ELECTRICAL SYSTEMS 



PRESSURE 
SWITCH 



TYPE IC/N 

THERMOSTATIC 

SWITCH 




POWER FROM 

LOCAL I.C. 

SWITCHBOARD 



Figure 8- 25 --1C alarm circuits 1EC and 1EW. 



27.38C 



Maintenance should be accomplished as in- 
structed by the applicable MRC's with attached 
Equipment Guide Lists and manufacturer's tech- 
nical manuals. 

Operators, watchstanders, and maintenance 
personnel should remember that when you use 
test-cutout switches on the alarm panels and 
switchboards to test an alarm circuit, only the 
alarm indicators and associated visual and audible 
signals will be testedo This type of test does not 



verify that the sensing device employed in th 
circuit will operate at the proper value, Th 
sensing device could be, as is the case in al 
too many instances, completely inoperable; ye 
the circuit would test good from the alarm panel 
A regular program should "be undertaken to teg 
alarm circuits on a regular basis by duplicating 
as closely as possible, the conditions which th 
alarm system was designed to indicate. By doin 
this, the entire system, including the sensin 
device and its operating point, is verified* 



CHAPTER 9 

SHIP'S INDICATING, ORDER, AND 
METERING SYSTEMS 



The modern naval vessel is an extremely 
complex machine. To properly operate a ship, 
watch personnel require vast quantities of in- 
formation relative to conditions within and without 
the ship* 

The Officer of the Deck must have a rapid 
means of transmitting orders to the throttleman 
and to the man on the helm, etc*, and just as 
rapidly, he must know that his orders have been 
received,. The actual speed and position of the ship, 
the distance traveled, the speed of the main 
engines, the wind speed and direction, the amount 
of fuel remaining aboard, the salinity of the feed- 
water, and a host of other information, are of 
great interest to personnel throughout the ship. 
Ship's Indicating, Order, and Metering Systems 
measure and transmit much of this information 
throughout the ship. 



TANK LEVEL INDICATING 
SYSTEMS 

The tank level indicating system, circuit TK, 
measures the amount of liquid in various ship- 
board tanks and transmits that information, 
electrically, to remote locations,, 

A typical tank level indicator consists of 
(1) a transmitter, which measures the liquid 
level in a tank and converts that information to 
an electrical signal; (2) a power supply; (3) an 
indicator meter or meters, calibrated in gallons 
or pounds of liquid; and, in some cases, (4) an 
alarm circuit that warns of unusually high or 
low liquid levels within the tank 

Several different types of tank level indicating 
systems^ whose transmitters employ different 
principles of operation to detect liquid level, are 
utilized aboard Navy ships. Of these systems the 
type IC/MC, or GEMS, tank level indication 
systems has proven to be one of the most 
accurate and reliable 



The GEMS tank level indicating system func- 
tions essentially the same as the basic circuit 
shown in figure 9-1. The movement of the float 
causes the resistance of the voltage divider 
network to vary In the circuit shown, the low 
level is indicated when there is less voltage drop 
between the contact points of the meter. A full 
tank would be indicated when all of the voltage 
drop across the resistor is being measured. 

Instead of having the float connected mechan- 
ically to the slider of a variable resistor as shown 
in figure 9-1, the actual transmitter of the GEMS 
system functions through magnetic mechanisms. 
The transmitter consists of a waterproof tube. 
Contained within the tube are many magnetically 
operated reed switches and a voltage divider 
network. A magnet is encapsulated within the 
material of the float. As shown in figure 9-2, 
the upward movement of the float and magnet 
within the tube results in the operation of the 
enclosed reed switches The reed switches are 
connected to the voltage divider network in such 



FLOAT 



D.C. POWER 
SUPPLY 



TANK' 



VOLTAGE 

DIVIDER 

RESISTANCE 




Figure 9-1. 



-Basic circuit for 
indicator. 



104.64 
liquid level 



159 



v- TRANSMITTER 
\ TUBE 



\ 




SWITCHES 
A & B CLOSED 




MAGNETIC REED 
SWITCHES 

FLOAT 



BAR 
MAGNET 



SWITCHES 
A, B & C CLOSED 



27.381 

Figure 9-2. Operational sequence of magnetic 
reed switches as float travels along transmitter 
tube* 



TRANSMITTER 

(HOUSING VOLTAGE 

DIVIDER) 



PRIMARY 

INDICATOR METER 
AND D.C. POWER SUPI 




TANK 



SECONDARY I 

INDICATOR 
METER 



I 



a way that, as each reed switch closes for an 
upward movement of the float, a quantity of 
resistance will be added, thereby increasing 
the voltage drop across the transmitter 

As might be expected, there is a * 'stepping" 
motion of the meter pointer as each quantity 
of resistance is added to or subtracted from the 
voltage dropping circuit. Since there are many 
reed switches in proportion to the length of the 
transmitter and since the change in the quantity 
of resistance is small as each reed switch is 
actuated, the "stepping" motion is barely dis- 
cernible. 

Figure 9-3 illustrates a typical GEMS liquid 
level indicator system with primary and secondary 
indicator meters. 

The GEMS system can distinguish between two 
liquids of different specific gravities, such as 
fuel oil and water, when a float material is used 
that will float in the denser liquid but not in the 
less dense. Transmitters with this type float 
are used in compensated fuel oil tanks to dis- 
tinguish between the fuel and water and indicate 
only how much fuel remains. 



SAFETY 

When maintenance is being performed on any 
tank level indicating system, and a tank will be 



Figure 9-3. Diagram of a GEMS liqu: 
indicator system. 



entered, be sure that the Gas Free I 
has tested the tank before maintenance p* 
enter. Follow all safety directives pr 



SALINITY INDICATOR 
SYSTEM 

The salinity indicator system, cir< 
indicates the amount of salinity in water 
aboard ship. The system is a necessity 
ship because all freshwater, when unde 
made from seawater Excessive salinit 
boiler feedwater causes pitting of tt 
and rapid deterioration due to elecl 
Salinity indicators are usually provide 
enginerooms and the firerooins to ct 
condensate from the main and auxilia 
denserso The indicators are also provide 
evaporator plants to indicate the degree < 
of the water at various selected point 
distilling system* 

The salinity indicator system operate 
principle that an increase of the ele< 
impurities (principally salt) in water ir 
the electrical conductivity of the watei 
electrodes are immersed in the wate 
tested and a stable alternating voltage i* 



160 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



across the electrodes, a stable alternating cur rent 
will flow through the water if the impurity content 
and the temperature of the water remain un- 
changed. 

The amount of current flow is indicated on a 
meter whose scale is graduated in chloride equiv- 
alent parts per million. If the saline content of 
the water increases because salt water is leaking 
into the system or because of faulty operation of 
the distilling plant, the conductivity between 
the electrodes increases, and the meter reading 
increases by an amount proportional to the 
increase in salinity. 

A complete salinity indicator system consists 
of one or more salinity cells which contain 
the electrodes, a salinity indicator panel which 
contains the meter, power supplies, control 
equipment, and, in some cases, alarm circuitry 
which warns of unusually high salinity conditions. 



SALINITY CELL 

The salinity cell (fig. 9-4) consists mainly 
of a 3-conductor interconnecting cable, packing 
nut, cell body, electrode assembly, and an auto- 
matic temperature-compensating resistor housed 
within the cell body. 

The packing nut and cell body properly support 
the electrode assembly in the ship's piping 
system and, along with the cell valve (discussed 
"below), form a watertight seal. They also provide 



a means of inserting and removing the cell from 
the ship's piping systems without loss of liquid. 

The electrode assembly consists of an inner 
electrode, outer electrode, and the automatic 
temperature compensating resistor. . The inner 
electrode consists of a platinum-plated button 
placed on the end of the cell body but insulated 
from it. The outer electrode is a platinum -plated 
cylinder that is connected to the cell body and 
surrounds the inner electrode. The outer electrode 
is pierced with holes to vent any gases trapped 
between the two electrodes and to permit free 
circulation of water over the electrodes. 

Two factors actually control the conductivity 
of the impure water. The firstf actor, the salinity, 
has been discussed. The second factor is the 
temperature of the solution. As the temperature 
of a saline solution increases, its conductivity 
decreases. This phenomenon causes the salinity 
system to indicate an impurity level that is less 
than that actually present. To compensate for this 
action, an automatic temperature-compensating 
resistor is placed inside the cell body. By its 
location within the cell, the automatic 
temperature-compensating resistor maintains its 
temperature at that of the surrounding water .The 
resistor's conductance varies by a factor that is 
proportional to diluted seawater. Since both the 
resistor and the diluted seawater are affected 
by temperature in a like manner, the resistor 
is connected in the circuit so that the net result 
of a temperature change is zero. In this way, 
the salinity equipment continually indicates the 
actual impurity content through a temperature 
range of 40 F to 250 F. 



PACKING NUT 




OUTER ELECTRODE 



INNER 
ELECTRODE 



ELECTRODE 
ASSEMBLY 



7.1 SOX 



Figure 9-4. Salinity indicator cell. 
161 



SHIPBOARD ELECTRICAL SYSTEMS 



CELL VALVE 

As stated earlier, the cell valve, in conjunction 
with the packing nut and cell body, provides the 
means to insert or retract the cell from the 
ship's piping systems without loss of water 
while maintenance is being performed. Figure' 
9-5 provides a view of a salinity cell installed 
in a ship's piping system through a cell valve. 

SALINITY INDICATOR 
PANEL 

As previously stated, a salinity indicator 
panel measures the conductivity of the water 
being tested by the salinity cell and displays 
this information as a reading on a meter. In 
some cases the indicator panel provides audible 
and visual alarms if the salinity of the water 
under test exceeds specified limits. There are 
many different types of salinity indicator panels 
available; two are discussed below. 

IC/E1U-S3 Salinity 
Indicator Panel 

The IC/E1U-S3 salinity indicator panel (fig. 
9-6) monitors the conductivity of one salinity 
cell continuously. This panel may be used in 
a system that contains only one salinity cell 
such as an electronics cooling water system, 
or it may be used in a larger system where 
a continuous reading of one particular cell 



NIPPLE 



PACKING 

CELL 
BODY 





27.382 
Figure 9-5. -Salinity cell installation. 



27.383 
Figure 9-6. IC/E1U-S3 indicator panel. 



of a system is desirable,. The unit contains 
a meter, a test pushbutton, calibration resistor 
network, and an isolation transformer. 

The test pushbutton and calibration network 
serve as a self-check circuit. This self-check 
circuit serves only to test the meter's accuracy, 
When the test pushbutton is depressed the meter 
should read 1.7 ppm. If it doe snot, the calibration 
resistor contained within the unit should be 



162 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



adjusted by maintenance personnel for this 
reading. 

As the electrodes of each salinity cell are 
immersed in water f leakage current may flow 
from the electrodes through piping to the ship's 
hull (ground). In fact, the outer electrode of the 
salinity cell makes actual metallic contact with 
the cell body and packing nut. When the cell 
is installed in a ship's piping system, a very 
low resistance path is provided for the 115 VAC 
applied to the outer electrode to ground. The 
isolation transformer of the unit isolates the 
ground paths provided by the salinity cells from 
the ship's supply voltages. In addition, it does 
not allow the ground paths of one cell to affect 
the reading of another cell, and it reduces the 
electrical shock hazards for personnel associated 
with this system* 



IC/D5RM Salinity 
Indicator Panel 

The IC/D5RM salinity indicator panel (fig. 
9-7), is designed to monitor five salinity cells 
of a distilling plant, although it may be used 
in a condensate system. The panel has an alarm 
system to warn of high salinity conditions and 
circuitry to control a solenoid trip valve winch 
is used to dump the distillate coming from the 
plant in the event its salinity exceeds a specified 
amount. The panel is modular in construction 
and contains a power unit, a meter unit, a valve 
position and meter test module, a relay module, 
and five identical salinity modules. 

Please refer to figure 9-7 as we discuss the 
IC/D5RM salinity indicator panel in the succeeding 
paragraphs. 



SILENCE 
SWITCH 




VALVE POSITION 
8 METER TEST 
MODULE 



RELAY MODULE 



SALINITY 
MODULE 



METER SWITCH 



Figure 9-7.- IC/D5RM salinity indicator panel. 
163 



7.151 



SHIPBOARD ELECTRICAL SYSTEMS 



The power unit has a white power-on indicator 
lamp and two indicating fuse holders. Contained 
within the unit is a transformer which provides 
power to operate the salinity module sand salinity 
cells. The transformer also isolates the grounds 
inherent to the salinity cells, as discussed earlier. 

The salinity modules, of which there are five, 
continuously monitor the salinity cell connected 
to it. If its alarm set point is exceeded, the module 
signals by flashing its red indicator light and by 
sounding an external audible signal that is common 
to all five module s e 

A high salinity condition is indicated initially 
by a flashing red indicator light and an external 
audible alarm. To clear the external alarm for 
other incoming alarms, the silencing switch on 
the module is placed in the SILENCE (down) 
position, causing the red indicator light to glow 
steadily. When the high salinity condition is 
corrected, the red light again begins to flash to 
remind the operator to return the silencing 
switch to the NORMAL (up) position. 

The 3-position, spring-loaded meter switch 
has a NORMAL (center) position, a TEST position, 
and a METER position. When placed in the TEST 
position, the meter switch causes the cell to 
behave as though a high salinity condition exists 
energizes the alarm circuit causing the red 
alarm light to flash and the alarm relay to sound 
the external alarm. The meter switch, when 
placed in the METER position, connects the 
meter unit to the associated salinity cell, and 
a salinity reading is indicated on the meter. 

The relay module contains an external alarm 
relay and a 2-second delay relay. The external 
alarm relay is controlled by the salinity modules. 
With the silence switch in the NORMAL position, 
an alarm condition in any one of the salinity 
modules will cause the external alarm relay 
contacts to close, sounding the external audible 
alarm. The 2-second delay relay is used in 
conjunction with the solenoid trip valve. Any 
one of the five salinity modules may be used to 
actuate the time delay relay. Usually, the wiring 
inside the panel is connected so that the salinity 
module that monitors the distillate, after it has 
passed through the final stages of the distilling 
plant, is selected to control the time delay 
relay. If an alarm condition lasts for more than 
2 seconds, in the selected module, the 2-second 
time delay relay causes the solenoid trip valve 
to be deenergized (tripped) . The tripping of the 
solenoid trip valve causes the distillate to be 
dumped to the bilges or overboard. When the 
alarm condition is cleared, the solenoid trip 
valve must be manually reset. A 2-second delay 



relay is used so that spurious alarms in the 
selected module will not trip the solenoid valve. 
The valve position and meter test module 
has a green valve position indicator lamp and a 
meter test switch. The dual purpose of the 
unit is to indicate whether the solenoid trip 
valve is in the NORMAL or TRIPPED position 
and to provide a means of testing the meter 
unit. 

When the solenoid trip valve is in the NORMAL 
position, the green indicator lamp is illuminated 
steadily; when in the ABNORMAL position, the 
green alarm light flashes; and when the valve 
is reset manually, the green alarm light is 
again lighted steadily. 

The meter test switch, when placed in the 
TEST position, connects the meter unit to a 
circuit which simulates a known salinity con- 
dition (1.7 ppm) to check the calibration of the 
meter. 

SAFETY 

As previously discussed, dangerous potentials 
are present on all the surfaces of the salinity 
cells. The ENTIRE SYSTEM should be deenergized 
and RED-TAGGED when any maintenance is 
performed on the salinity cells or inside the 
salinity panel. Also, personnel should be cautioned 
prior to working on salinity cells to take adequate 
precautions to avoid injury from hot pipes, steam 
and/or high pressures which may be present in 
the ship's piping systems. 



RUDDER ORDER AND 

RUDDER ANGLE 
INDICATOR SYSTEMS 

The rudder order system (circuit L) and the 
rudder angle indicator system (circuit N) utilize 
synchros, as do many other 1C circuits, to 
transmit information. Synchros are electromag- 
netic devices which are used primarily to transmit 
angular position data. Physically, as shown in 
figure 9-8A, a synchro resembles a small electric 
motor, butfunctions as a transformer, the primary 
of which is connected to the shaft whose angular 
position is to be transmitted. The secondary of the 
synchro surrounds the primary of the synchro. 
When an a.c. voltage is applied to the primary, 
its angular position in respect to the secondary 
determines the voltage induced in the secondary 
Each time the angular relationship between the 
synchro's primary (rotor) and secondary (stator) 



164 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



BALL 
BEARING 




STATOR AND 
SECONDARY WINDINGS 



SLIP RINGS 



ROTOR AND 
PRIMARY WINDINGS 



CUTAWAY VIEW OF SYNCHRO 



SYNCHRO 
TRANSMITTER 




INTERCONNECTING 
LEADS 



HANDWHEEL 



115 VOLT 
SUPPLY 



RECEIVER 
INDICATOR 
DIAL 



B SIMPLE SYNCHRO SYSTEM 



Figure 9-8 e Synchros. 



236.399 



is changed, the induced voltages in the stator 
change. 

Figure 9-8B shows a simple synchro system * 
Tlie rotor of the transmitter and the rotor of the 
receiver are connected to the a.c. supply voltage. 
The stator of the receiver is connected to the 
stator of the transmitter. When the handwheel 
in figure 9-8B is turned, the rotor-stator angular 
positions of the transmitter and the receiver are 



no longer the same, the voltages induced in their 
respective stators will not be the same These 
two different stator voltages result in an un- 
balanced condition between the transmitter and 
receiver. As a result of this unbalance, a torque 
is produced electro-magnetically between the 
rotors and the stators of the transmitter and 
the receiver. The rotor of the transmitter is held 
in position which causes the receiver's rotor to 
move to a position to eliminate the unbalanced 



165 



SHIPBOARD ELECTRICAL SYSTEMS 



condition. As a result, the movements of the rotor 
of the transmitter are followed by the rotor 
of the receiver. The above information is a very 
simple explanation of synchro principles. Detailed 
information concerning the operation and main- 
tenance of synchros is contained in Basic Elec- 
tricity, NAVPERS 10086, Synchros, Servo, and 
Gyro Fundamentals, NAVPERS 10105, and 
Military Standardization Handbook for Synchros, 
MIL Hdbk 225-(AS). 

RUDDER ORDER SYSTEM 

Under normal conditions the rudder of a ship 
is controlled remotely from the helm on the bridge. 
If the remote steering control system should fail, 
the rudder order system (circuit L) electrically 
transmits rudder orders to the steering gear 
room where watch personnel can control the 
steering gear. 

The two major units of the rudder order 
system serve a dual purpose in that components 
of both units are used in conjunction with the 
rudder angle indication system (circuit N). 

The rudder order transmitter-rudder angle 
indicator (fig. 9-9) is installed on the bridge 
to transmit the ordered rudder angle to watch 
personnel in the steering gear room. This indi- 
cator contains a synchro receiver, which is a 
component of the rudder angle indicating system 
(circuit N), and a synchro transmitter, which 
is a component of circuit L. 




PUSHSWITCH 



The rudder order-rudder angle indicator (fi 
9-10) , installed in the steering gear room , contaii 
two synchro receivers. One of the receivers 
used in conjunction with the rudder indicatii 
system (circuit N). The other receiver, a con 
ponent of circuit L, receives the transmit!* 
order from the bridge unit. 

The control knob on the rudder ord< 
transmitter- rudder angle indicator (fig. 9- 
manually positions the pointer marked ORD i 
well as the rotor of the synchro transmitter 
the bridge unit. The transmitter produces a sign 
which is sent to the circuit L receiver in ti 
steering gear room. The signal causes the point* 
(ORD) on the receiver to move automatically 
a position that corresponds to the position of ti 
pointer on the bridge. 

The pushswitch in figure 9-9 is used j 
conjunction with a bell in the steering* gear roon 
Each time a new rudder order is transimtte< 
the pushswitch is depressed to alert steeric 
gear watch personnel to the new order. 




7.126.1 

Figure 9-9. Rudder order transmitter-rudder 
angle indicator. 



7.126.5 

Figure 9-10. Rudder order -rudder angle 
indicator. 



166 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



RUDDER ANGLE 
INDICATOR SYSTEM 

The rudder angle indicator system (circuit N) 
electrically transmits the actual angular position 
of the ship ' s rudder to de signated stations through- 
out the 



The rudder angle transmitter (fig d 9-11) 
consists of a synchro transmitter mechanically 
linked to the rudder stock in such a manner 
that the synchro transmitter shaft follows the 
movement of the rudder. It transmits rudder 
angle data to various ship's indicators,, 

The rudder angle indicator (fig 9-12) consists 
of a fixed dial and a pointer mounted on the 
shaft of a synchro receiver* The synchro receiver 
positions the pointer on the dial face in response 
to the transmitted rudder angle. 

The angular position of the rudder is also 
transmitted to the receivers associated with 
circuit N in the units shown in figures 9-9 and 
9-10* 

Figure 9-13 is a block diagram of the rudder 
order and rudder angle indicating systems, show- 
ing the various units as discussedo 

The combination rudder order transmitter- 
rudder angle indicator, as well as many other 
indicators and components, is mounted in a 
steering control console (fig. 9-14) on new con- 
struction ships, The console contains much of 




7.126.6 
Figure 9-1 2. Rudder angle indicator (circuit N). 



the information and controls required for a 

helmsmano 



PROPELLER REVOLUTION 

INDICATOR SYSTEM 




7.129 
Figure 9-ll Rudder angle transmitter. 



The propeller revolution indicator system 
(circuit K) indicates instantaneously and con- 
tinuously the (1) revolutions per minute, (2) 
direction of rotation, and (3) total revolutions 
of the individual propeller shafts . The information 
is indicated in the enginerooms, pilothouse, and 
other required locations* 

The propeller revolution indicator system 
usually consists of two different types of equip- 
ment: (1) synchro- type equipment and (2) magneto- 
voltmeter type equipment. The synchro-type 
equipment is installed in large combatant ships 
and in many newly constructed small ships. 
The magneto- voltmeter type equipment is less 
complicated and is installed in small ships. 



167 



SHIPBOARD ELECTRICAL SYSTEMS 



PUSHSWITCH 

O 



RUDDER ORDER TRANSMITTER- 
RUDDER ANGLE INDICATOR 



BRIDGE 



CIRCUIT N 
' INFORMATION 



TO VARIOUS RUDDER ANGLE 
INDICATORS 



STEERING GEAR EQUIPMENT 

RUDDER ORDER - 
RUDDER ANGLE INDICATOR 




CIRCUIT L 
"INFORMATION 



ROOM 



STEERING RAM ROOM 





Figure 9-13. Block diagram of basic rudder order-rudder angle indicating system. 



27.2 



SYNCHRO-TYPE 
EQUIPMENT 

A representative synchro-type propeller revo- 
lution indicator system installed aboard a DDG 
as illustrated by the block diagram in figure 
9-15. The system consists of two transmitters, 
two indicator-transmitters, and four indicators. 
The transmitters are driven by the main engines 
and are electrically connected to indicator- 
transmitters at their respective throttle stations. 



Indicators, such as those in figure 9-16, are a 
installed on the gage boards in both engineroc 
and in the pilothouses. Each indicator has 
backing signal lamp which, when lighted, dene 
astern rotation of the propeller shaft. 

A synchro signal representing and proportic 
to the rotary motions of the propeller si 
is transmitted by the transmitter (fig. 9-1 
to the associated indicator-transmitter (: 
9-16B), which continuously indicates the tc 



168 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



RUDDER ORDER TRANSMITTER- 
RUDDER ANGLE INDICATOR 



REMOTE IMD. WAG. COMPASS 
REPEATER 



SHIPS COURSE 
INDICATOR 



GRAB BARS 



HELM AIMGLE 
INDICATOR 



STEERING 
CONTROL 

"POWER ON" 
INDICATOR 

LIGHTS 



RUDDER ORDER TRANSMITTER 
OPERATING KNOB 

EMERGENCY STEERING SWITCH 



RUDDER ORDER ATTENTION 
PUSHSW1TCH 



MASTER DIMMER CONTROL 



RUDDER ORDER TRANSMITTER 
"POWER ON" PILOT LIGHT 



COURSE TO STEER 
INDICATOR 



STEERING WHEEL 




DOOR FOR ACCESS 
TO TERMINAL 
BOARDS FOR 
SHIPS WIRING 



7.133 



Figure 9-1 4 Steering control console,, 



revolutions of the propeller shaft on a counter 
and converts the received synchro signal into 
an angular indication of RPM. The RPM reading 
is also transmitted to indicators via a synchro 
transmitter contained within the indicator- 
transmitter o 

The indicator (fig. 9-16C), repeats the rpm 
reading received from the associated indicator- 
transmitter. The entire system operates on the 
ship's single-phase, 11 5- volt, 60-hertz power 
supply. 



MAGNETO- VOLTMETER 
TYPE 

The magneto- voltmeter propeller revolution 
indicating equipment consists of a magneto-type 
transmitter geared to each propeller shaft and 
electrically connected to remotely located indica- 
tors which consist of a voltmeter calibrated in 
revolutions per minute. 

The magneto is a permanent magnet type 
d.c. generator which is driven at a speed pro- 
portional to that of the propeller shaft. 



169 



SHIPBOARD ELECTRICAL SYSTEMS 




Figure 9-15, Block diagram of propeller revolution indicator system. 



27.335 



The indicators receive this voltage and indicate 
on the voltmeter scale the rpm of the propeller 
shaft. A total revolutions counter registers the 
total number of propeller revolutions locally 
at the magneto transmitter unit and a synchro 
transmitter transmits these revolutions to a 
synchro receiver which drives the associated 
total revolutions counter in the remote indicator. 



and wind direction and speed indicator. Usually 
two wind direction and speed detectors are 
mounted on the foremast, one on the port side 
and one on the starboard side,, The wind direction 
and speed transmitter is installed in the 1C 
room. The wind direction and speed indicators 
are installed in various spaces as required by the 
type of ship* 



WIND DIRECTION AND 

SPEED INDICATOR 

SYSTEM 

The wind direction (circuit HD) and speed 
(circuit HE) indicator system, indicates instan- 
taneously and continuously the (1) wind direction 
in degrees relative to the ship's heading, and 
(2) wind speed in knots relative to the ship. 

The type-B wind direction and speed indicator 
system consists of a wind direction and speed 
detector, wind direction and speed transmitter, 



WIND DIRECTION AND 
SPEED DETECTOR 

The wind direction and speed detector (fig. 
9-17) consists of a thin-gage Monel metal housing 
formed into a streamlined wind vane with a 
relatively large tail surface mounted on a vertical 
support assembly. The rotor assembly, attached 
to the head of the vane is held directly into 
the wind by the vane assembly and converts 
the wind speed into rotary motion. The speed 
of rotation of the rotor assembly is proportional 
to the velocity of the wind striking the rotor 
blade s 



170 




TRANSMITTER 

A 





INDICATOR -TRANSMITTER 

B 



INDICATOR 

c 



Figure 9-16. Propeller revolution indicating equipment. 



7.126.7 



The direction synchro transmitter, mounted 
in the vertical support assembly, is directly 
coupled to the vane so that when the wind positions 
the vane, the synchro transmitter rotor is dis- 
placed the same angular amount. The angular 
positions are transmitted electrically to a synchro 
control transformer in the wind direction sub- 
assembly of the transmitter (fig. 9-18). Because 
wind directions are indicated in relative bearings, 
the direction synchro transmitter in the detector 



is set to transmit zero when the rotor assembly 
of the detector unit points to the bow of the ship* 

The speed synchro transmitter, mounted in 
the head of the vane, is coupled through gears 
to the rotor assembly. The reduced rotary 
motions are transmitted electrically to a synchro 
receiver in the wind speed subassembly of the 
transmitter unit (fig. 9-18). 

The mbunting and the vertical support assem- 
blies of the wind direction and speed detector are 



171 



SHIPBOARD ELECTRICAL SYSTEMS 



ROTOR 

PLATE 

BEARING 

FLANGE 
ROTOR 
ASSEMBLY 

INNER 
HUB 



HOUSING 



CENTER WANE 
SUPPORT ASSEMBLY 



ROTOR 
SHAFT 



VANE 

SHAFT 

ASSEMBLY 



COLLECTOR 
RING 
ASSEMBLY 



^VERTICAL 
SUPPORT 
ASSEMBLY 




MOUNTING 
ASSEMBLY 



"STERN 

PIPE 
FITTING 
FOR 

TERMINAL 
TUBE 



EXTERNAL VIEW 



INTERNAL VIEW 



B 



7,145 



Figure 9-17. Wind direction and speed detector. 

172 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



WIND DIRECTION 8 
SPEED DETECTOR 



WIND DIRECTION a 
SPEED INDICATOR 



r 




\ 

DIRECTION 

SYNCHRO 

TRANS. 



DIRECTION 
SYNCHRO 
TRANSMITTER 
CT }- --) [ TX 




WIND DIRECTION SUBASSEMBLY 



SHADED-POLE 
, FOLLOWUP 
MOTOR 



SYNCHRONOUS 
MOTOR ' 



REFERENCE 
VOLTAGE 



SPEED 
SYNCHRO 
. RECEIVER 
( T R V- 





SPEED 

SYNCHRO 

TRANSMITTER 



WIND SPEED SUBASSEMBLY 



| WIND DIRECTION AND SPEED TRANSMITTER 

Figure 9-18. Block diagram of type-B wind direction and speed indicator system . 




provided with flanges for bolting the two sections 
together. 

WIND DIRECTION AND 
SPEED TRANSMITTER 

The wind direction and speed transmitter 
(fig. 9-18) consists of a wind direction sub- 
assembly and a wind speed subassembly mounted 
on individual baseplates to form a complete 
unit enclosed in a metal case designed for 
bulkhead mounting. 



Wind Direction Subassembly 

The wind direction subassembly is essentially 
a servo unit comprised of a synchro control 
transformer, followup amplifier, followup motor, 
and synchro transmitter. 

Please refer to figure 9-18 as we continue 
our discussion. 



When the rotor of the wind direction synchro 
(CX) located in the wind speed and direction 
detector, and the rotor of the synchro control 
transformer (CT), located in the wind direction 
subassembly, are in correspondence, the output 
voltage from the synchro control transformer 
will be zero. When a change in wind direction 
causes the vane of the wind speed and direction 
detector to change its position, the direction 
synchro transmitter and the synchro control 
transformer rotors will no longer be in cor- 
respondence and a voltage is induced in the 
rotor of the synchro control transformer. The 
output voltage from the rotor of the synchro 
control transformer is either in phase or 180 
out of phase with the source (reference) voltage, 
depending on the direction in which the vane 
has turned. Thus, the phase of the output of 
the control transformer reverses with respect 
to the reference voltage as the direction of 
displacement reverses. The magnitude of the 
output voltage from the synchro control trans- 



173 



SHIPBOARD ELECTRICAL SYSTEMS 



former represents the amount by which the 
shafts of the synchro control transformer and 
the direction synchro transmitter are out of 
correspondence,, Thus, the direction in which 
the transmitter shaft is turned determines the 
phase of the output voltage from the synchro 
control transformer with respect to the reference 
voltage, and the amount of displacement deter- 
mines the magnitude of the output voltage from 
the synchro control transformer. 

The synchro control transformer voltage, 
caused by the angular displacement, is amplified 
and fed to the followup motor which drives the 
synchro transmitter and control transformer 
through gears into correspondence with the 
synchro transmitter in the vane. The direction 
in which the followup motor drives is determined 
by the phase of the output voltage from the 
synchro control transformer; the speed at which 
the followup motor drives is determined by the 
magnitude of the output voltage from the synchro 
control transformer. The synchro transmitter 
located in the wind direction subassembly trans- 
mits an angular displacement representing wind 



direction to the synchro receiver sin the remote! 
located indicators. 

Wind Speed Subassembly 

The wind speed subassembly (fig. 9-19) utilize 
a friction disk and roller integrator to convei 
the rotary motion produced by wind velocit 
to an angular quantity that may be displaye 
on a dial. The subassembly receives the rotax 
motion from the speed synchro transmitter c 
the detector. The rotary motion, which represent 
wind velocity, is converted into an angula 
displacement by the friction disk and rolle: 
integrator assembly. The mechanical output o 
the integrator positions the rotor of the synchro 
transmitter which transmits an angular displace- 
ment signal representing wind velocity to thi 
various indicators throughout the ship. 

WIND SPEED AND 
DIRECTION INDICATOR 

The wind direction and speed indicator (fig, 
9-20) is a dual unit consisting of a wind direction 



WIND DIRECTION 
AND SPEED DETECTOR 

I 1 




SPEED SYNCHRO 
TRANSMITTER 



j ! 

I WIND SPEED I 
I INDICATOR I 



I 



CONSTANT SPEED 
REDUCTION (SYNCHRONOUS) 

GEAR MOTOR 

ASSEMBLY 





I ^ 1 SYNCHRO 

TRANSMITTER 



PINION 



REDUCTION 

GEAR 

ASSEMBLY 



CIRCULAR 
^ --- , RACK 



WORM 
GEAR 



SPIRAL 
GEAR 



DISK DRIVING 

DRIVE DISKS 

GEARS 

ROLLER GEAR ASSEMBLY - 



GEARS 



Figure 9-19. Wind speed subassembly, 
174 



7.147 



Chapter 9 -SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 




UNDERWATER LOG AND 

DUMMY LOG SYSTEMS 

The underwater log system (circuit Y) meas- 
ures and indicates the speed of the ship through 
water and the distance traveled through the 
water. It transmits these indications to the 
various speed indicators, distance indicators, 
and weapons and navigational systems, as re- 
quired. 

The dummy log system (circuit 4Y) produces 
simulated speed and distance signals for the 
various ship's systems that require either ship's 
speed or distance inputs. The system serves two 
purposes (1) to simulate ship's movement 
through the water in order to train personnel and 
align equipment and (2) to serve as a backup for 
the underwater log system. The dummy log may 
be used to supply an estimated speed and distance 
signal to ship's systems in case the underwater 
log system becomes inoperable. 

In actual practice aboard ship, circuits Y 
and 4Y are usually tied together by a switching 
arrangement that permits information pertaining 
to the ship's speed and distance from either 
source to be fed throughout the ship to a common 
set of indicators and equipment. 



7.148 
Figure 9-20. Wind direction and speed indicator. 



subassembly and a wind speed subassembly. The 
two subassemblies are identical except for the 
dials. Each consists of a synchro receiver which 
indicates on a fixed dial by means of a revolving 
pointer attached directly to its shaft. The sub- 
assemblies are mounted on individual baseplates 
and enclosed in a metal housing to form a 
complete wind direction and speed indicator 
unit. 

SAFETY 

The maintenance of the wind speed and direc- 
tion indicating system, as well as other equipment 
under the cognizance of E division, requires that 
personnel work aloft at one time or another. The 
regulations for men working aloft contained in 
Navy Safety Precautions For Forces Afloat, 
OPNAV Instruction 5100.19, and in ship's in- 
structions, must be followed for these operations. 
Personnel who are to work aloft should be 
thoroughly familiar with all regulations and 
safety precautions concerned. 



UNDERWATER LOG 

SYSTEM 

The majority of all current underwater log 
systems employ the electromagnetic principle 
to sense the ship's speed through the water. 
Several different configurations employing this 
principle of operation have been produced by 
various manufacturers for the Navy. 

Electromagnetic Principle 

The electromagnetic principle used in the 
underwater log system is the same basic principle 
by which a generator produces a voltage. If a 
conductor is moved through a magnetic field, a 
voltage will be induced in the conductor. The 
magnitude of the induced voltage will vary with 
the number of active conductors moving through 
the magnetic field, the strength of the magnetic 
field, and the speed at which the conductor is 
moved through the magnetic field. An increase 
in the number of conductors, the strength of 
the magnetic field, or the speed of the conductor 
through the field will result in an increase in 
induced voltage. 



175 



SHIPBOARD ELECTRICAL SYSTEMS 



The electromagnetic underwater log functions 
by placing a magnetic field in seawater. Seawater 
conducts electricity very well and is used as 
the conductor. When the ship is not moving through 
the water, there is no relative motion between 
the magnetic field and the conductor; therefore, 
no voltage is induced in the conductor (seawater). 
As the ship begins to move, relative motion takes 
place and a voltage is induced in the seawater. 
An increase in the ship's speed increases the 
induced voltage directly proportional to the in- 
crease in ship's speed By comparing the induced 
voltage to a known voltage, an accurate determi- 
nation of the ship's speed can be made* 



Sea Valve and 
Rodmeter Assemblies 



Mounted in the hull of the ship, the sea valve 
and packing assembly (fig. 9-21 and 9-22) provide 
a watertight support for the rodmeter, enabling 
the rodmeter to be retracted or extended through 
the open sea valve,, The sea valve, when closed 
also seals the hull when the rodmeter is retracted. 




JUNCTION BOX 



PACKING 




RODMETER 



VALVE BODY 



Figure 9-21. Sea valve. 



27.271 



SHIP'S HULL 



140.159 

Figure 9-22. Exploded view of the sea valve and 
packing assembly with rodmeter installed. 



The rodmeter (fig. 9- 23) is made of corrosion- 
resistant Monel metal and is available in different 
lengths. The main components of the rodmeter are 
the rod weldment, the junction box, and the 
sensing unit. 

The rod weldment makes up most of the 
length of the rodmeter< It is a hydrofoil cross 
section, nickel-copper, watertight tube. The 
sensing unit is cemented to the lower end of 
the rod weldment, and the junction box is bolted 
to the upper end. Two shielded electrical cables 
connected to the sensing unit pass through the 
rod weldment and terminate in the cable con- 
nectors. 

The sensing unit (fig. 9-24) is a plastic molding 
(boot) made of an epoxy resin mixed with glass 
fiber a In it are imbedded a coil and two Monel 
metal buttons. 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



JUNCTION BOX 




COVER 

CABLE 
CONNECTORS 



-ROD 
WELDMENT 



SPEED SIGNAL 
TO INDICATOR 
TRANSMITTER 



SENSING UNIT 
OF RODMETER 




SUPPLY 
FROM 
INDICATOR 
TRANSMITTER 




INDUCED EMF 
APPEARS ACROSS 
PICKUP BUTTONS 



\ 



<^ 

& 



INDUCED VOLTAGE CIRCUIT 
IN PLANE OF WATER 



DIRECTION OF 
SHIP'S MOVEMENT 



SENSING 

UNIT 



PICKUP 
BUTTON 



Figure 9-23 c Rodmeter. 



27.272 



The .coil of the sensing unit is excited with 
a 60-hertz a.c. voltage, thus creating a magnetic 
field in the seawater around the rodineter sensing 
unit* 

As the ship and magnetic field move, the 
water on both sides of the rodineter is cut by 
lines of flux, and a voltage proportional to the 



27.273 
Figure 9-24. Cutaway view of sensing unit. 



velocity of the water is generated on both sides 
of the rodineter. The pickup buttons located 
on each side of the rodmeter make contact 
with the water and pick up the voltage being 
generated in the water. This voltage (propor- 
tional to the ship's speed through the water) 
is applied to the indicator-transmitter (discussed 
later) where the actual ship's speed and distance 
are calculated,, 



Fixed Rodmeter 



The fixed rodmeter is installed on nuclear 
submarines and new construction surface craft. 
It replaces the sea valve and rodmeter assem- 
blies discussed above. As shown in figure 9-25, 
the rodmeter is mounted through the hull of the 
ship with the sensing element exterior to the 
hull and the electrical connection inside the 
ship* The sensing unit of the rodmeter is basically 
the same as that of the previously discussed 
rodmeter. The major advantage of the fixed 
rodmeter installation is the increased water- 
tight integrity of the hull. 



177 



SHIPBOARD ELECTRICAL SYSTEMS 



-"0" RINGS 



STOP 



SIDE SCREW 
W/"0" RING 

HULL 




RETAINING 
RING 




SENSING 
UNIT 




FORWARD 
VIEW 



PORT 
VIEW 



Figure 9-25. Fixed rodmeter. 



27.385 



NOTE: Seawater dools the rodmeter and pre- 
vents the sensing element from overheating 
when the system is operating. To prevent pos- 
sible damage to the sensing element of the 
rodmeter the underwater log equipment should 
never be energized unless the sensing element 
is emersed in water. 

Indicator- Transmitter 

The indicator-transmitter contains all the 
electrical and mechanical components necessary 
to measure the voltage from the rodmeter and 



to convert it into ship's speed and distance 
signals. 

Two underwater log systems (the Litton 
Indicator -Transmitter and the Chesapeake 
Indicator-Transmitter) will be discussed below, 
The rodmeters of both systems are interchange- 
able. The type shown in either figure 9-23 
or 9-25 may be used. The construction of the 
indicator-transmitters is the most distinctive 
difference between the two systems. 

LITTON INDICATOR-TRANSMITTER. -The 
Litton indicator-transmitter (fig. 9-26) is the 



178 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



DISTANCE 

MILES 
COUNTER 



DUMMY SIGNAL 
UNIT 




DISTANCE SERVO 
MOTOR 



SPEED DIAL 



SPEED SERVO-'] \ ^ 

MOTOR nj| 

^ 



MECHANICAL 

UNIT 
ASSEMBLY 



CASE 



ELECTRONIC 

UNIT 
ASSEMBLY 



ACCESS COVER 
FOR WIRING 



Figure 9-26.- Litton indicator-transmitter (cover removed) . 



7.153 



older in design of the two units. It has been 
installed in Navy ships for approximately 20 
years,, 

The Litton underwater log system is com- 
prised of the components shown in figure 9-27. 
The system functions as follows: The rodmeter 
produces an a.c. signal voltage proportional 
;0 the ship's speed. This signal is amplified and 
ed to the speed servomotor, which drives 



the speed synchro transmitter, the dual-pointer 
dial, and the integrator. The integrator converts 
the input from the speed servo into a distance- 
traveled output which drives a synchro- 
transmitter and a 6-drum counter to display 
distance traveled in nautical miles. A dummy 
signal circuit (not shown) performs no function 
in normal equipment operation but provides 
simulated signals that can be used in checking 
the functioning of the system . 



SHIPBOARD ELECTRICAL SYSTEMS 



ELECTRICAL SIGNAL 



,A^ 


MECHANICAL LINKAGE 

40K/360 60HZ 
SPEED 
SIGNAL 
TO SHIP'S "^ 
WIRING 

INPUT 
TRANSFORMER 


j\ SPEED 
71 SIGNAL 




l 



DISTANCE 

SYNCHRO 

TRANSMITTER 





y CONSTANT 
^SPEED 
MOTOR 




INDICATOR-TRANSMITTER 



I 



Figure 9- 27. Block diagram of Litton Underwater Log System. 



27.27' 



Refer again to figure 9-27. The input trans- 
former functions as an error detector. It receives 
the speed voltage generated by the rodmeter 
and a response signal which is a measured 
voltage that represents the present position 
of the response potentiometer. 

When the response potentiometer is properly 
positioned, the response signal cancels out the 
speed signal in the input transformer and there- 
fore the error signal (output signal) from the 
input transformer will be zero. When the speed 
signal and the response signal are not of the 
same magnitude, an error signal is produced by 
the input transformer. The error signal is 
magnified by the servoamplifier until it is of 
sufficient magnitude to drive the speed servo- 
motor. The speed servomotor drives the dial, 
speed synchro transmitters, integrator, and the 
response potentiometer in accordance with the 
error signal through gearing until the response 
signal again equals the speed signal. For any 
change in speed, an error signal is developed 
which causes the servomotor to drive the gear 



train until the signal from the response po 
tentiometer again equals the speed signal,, 

In this manner, the indicator-transmitte: 
continuously indicates ship's speed on the dial 
and the speed synchro transmits ship's speed t 
the various ship's repeaters. 

The integrator is used in the indicator- 
transmitter to change an angular displacemen 
into a rotary motion The roller is positionei 
on the disk of the integrator by the speei 
servomotor. The position of the roller represent! 
ship's speed. The position nearest the cente: 
represents zero ship's speed, while a positioi 
near the edge represents 40 knots. Dependini 
on ship's speed, the roller of the integrate] 
is driven by the disk at a speed that represents 
ship's distance traveled. The integrator outpu 
is used to drive a miles counter and a synchrc 
transmitter which transmits a corresponding 
signal to remote receivers. However, because 
a direct load on the integrator output will likely 
cause the roller to slip, a distance servo has 



180 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



been inserted between the integrator and its 
load. The distance servo is used to drive the 
counter and distance synchro transmitter. In 
this way the integrator is mechanically isolated 
from its load. 

The dummy signal circuit (not to be confused 
with the dummy log system) produces voltage 
signals which simulate speed outputs from the 
rodmeter. Such signals can be used to check 
the performance of the speed and distance servos. 
The dummy signal circuit provides a simulated 
speed signal that causes the speed servo to 
stabilize at any of four dial readings (0, 5 t 
15, or 30 knots) and permits measurement of 
the accuracy of distance servo and integrator 
functioning. The dummy signals are not intended 
for calibration purposes; they only check the 
functioning of the equipment, and proper operation 
of the equipment with dummy signals does not 
necessarily mean that it will properly measure 
and indicate ship's speed through the water, 

CHESAPEAKE INDICATOR- 
TRANSMITTER. The Chesapeake indicator- 
transmitter (fig. 9-28) uses solid state devices 




REMOTE CONTROL 
UNIT 



INDICATOR- 
TRANSMITTER 



ROOMETER 




140.158 

Figure 9-28. Major components of the Chesapeake 
Underwater Log System. 



and its circuits reflect changes in the state 
of the art that took place between the development 
of the Litton and the development of the Chesa- 
peake* As you can see in figure 9-29 f the basic 
principles of operation in the two are very 
similar The principal differences between the 
two are that the Chesapeake unit: can supply 
five different synchro speed output signals; has the 
dummy log system {circuit 4Y) incorporated 
into its circuitry; uses logic circuits in the 
speed servoamplifier; and uses a solid state 
integrator, which also uses logic circuits, instead 
of the mechanical integrator of the Litton 
unit. 

In operation the speed, response, and error 
signals are developed inside the Chesapeake 
unit essentially as described for the Litton unit. 
The speed servoamplifier contains logic circuits 
which convert the a.c. error signal into d.c. 
pulses. The logic circuits are controlled by an 
oscillator which determines the rate at which 
the pulses are produced. The polarity of the 
pulses depends on the polarity of the error 
signal. Both the pulses and error signal are 
always of such polarity that the servomotor 
drives in the direction that will eliminate theiru 
Tlie speed servomotor (a d.c. stepping motor) 
is stepped by the d c. pulses. Each pulse from 
the servoamplifier causes the servomotor to 
step 1.8 in response to the pulses. As previously 
stated the rate of pulses from the amplifier, 
and therefore, the speed at which the servomotor 
steps, is dependent on the oscillator. The oscil- 
lator can produce two different frequencies. 
The higher of the two frequencies triggers the 
logic circuits at such a rate that pulses are 
produced which cause the servomotor to respond 
to speed changes at a rate of 40 knots per minute. 
The lower frequency of the oscillator limits 
the response of the logic circuits, so that the 
rate at which the pulses are produced will 
drive the servomotor at a rate of 8 knots per 
minute. 

The slow speed is used to smooth out oscil- 
lations of the rodmeter signal which are caused 
by ship's motion (other than forward motion) 
or water turbulence. The servomotor drives 
the response potentiometer, speed dial, and the 
five synchro speed transmitters, as well as 
provides a mechanical input for the solid state 
distance integrator. 

Five different speed signals are produced 
by the speed synchro transmitters a 60-hertz 
signal at 40 knots/360 and 100 knots/360 and 
a 400-hertz signal at 10 knots/360 , 40 knots/360 , 



181 



r 




*U MVU I 0V Hi. 


VjyiSjp 








100 KNOT 60 HZ 


H3t i 

MUST 




DIAL 








5 






40 KNOT 400 HZ (jf^ 1 


I SPEED 
f SYNCHRO 








1 


TRANSMITTERS 






100 KNOT 400 HZ 


<Q| 1 


SYNCHRO 




1 


"""* TRANSMITTER 

x jT'>-~S7*^ 


10 KNOT 400 HZ 


nyrfSi i y 


HIQTA IMPF" -^ -/ // 


7 (l(ur\ 




vw 


SIGNAL TO- 








SHIP'S-* \ V 






REMOTE CONTROL | 


WIRING ^ 


L^v 




UNIT 

l^^d 
| 


-^HA ND C R ANK 






A-C r n ~ r //X ^ 


-x. 




\ ^ ^ 


INPUT 
TRANSFORMER 


ERROR ^ f 


'* A m n ere / sp 


RVO 1 SOLID STATE - 




PULSES / r- 

/- Q r- r- p. . hb^. .j,,,. I SK 


^SIGNAL 


SPEED ' w ^ 
SERVO / \MC 


TOF J DISTANCE " 
V INTEGRATOR / 






AMPLIFIER 




. _ 


1 4 


A ~ c 4 4 


/RESPONSE\ . 
POTENTI- ' 





RESPONSE SIGNAL 



OMETER 



RODMETER 



MILES COUNTER 



L 



INDICATOR -TRANSMITTER 



Figure 9-29. Block diagram of Chesapeake Underwater Log System. 



and 100 knots/360 . The 40-knot/360 60-hertz 
output drives the ship's speed repeaters* The 
other outputs supply speed information to fire 
control and navigation equipment. 

The solid state distance integrator receives 
a mechanical input from the speed servo * This 
mechanical input is converted to an electrical 
signal which represents the ship's speed. The 
electrical speed signal is measured inside the 
solid state integrator where pulses are produced 
at a rate proportional to the magnitude of the 
speed signal. These pulses are applied to the 
distance stepmotor, which drives the distance 
synchro transmitter and miles counter at a 
rate which corresponds to the distance traveled 
through water. 

When the Chesapeake underwater log system 
is operating as a dummy log system, the speed 
input signal from the rodmeter is disconnected 
from the indicator transmitter. An estimated 
ship's speed may be set into the indicator- 
transmitter either manually through the use 



of the handcrank or through the remote c 
unit shown in figures 9-28 and 9-29 
indicator-transmitter transmits both the 
mated speed and the ship's distance ba 
the estimated speed to the ship's speed rej 
and equipment. 



DUMMY LOG SYSTEM 

Before the development of the Ches 
underwater log system, a separate dum] 
system was installed aboard ships a The i 
consists of a speed transmitter and a di 
transmitter o The speed transmitter was no 
located at the main engineroom control 
and was used to set the estimated ship's 
into the system . The distance transmitter n 
the control signal from the speed trans: 
The distance transmitter then transmittec 
and distance to the ship' s repeaters andequi 



182 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



UNDERWATER LOG 
SPEED CONVERTER 

The underwater log speed converter, like 
the dummy log system, is required on most 
ships that do not have a Chesapeake underwater 
log system. All underwater log and dummy 
log systems prior to the development of the 
Chesapeake underwater log system contained 
only one speed transmitter synchro. All those 
systems transmitted speed as a 40 -knot/360 
(1 knot graduation for every 9 on dial face), 
60-hertz signal. However, newer equipment was 
developed that required speed information other 
than 40-knots/360 60-hertz. The speed converter 
acts as an interface unit between the newer 
equipment and the older underwater/dummy log 



systems. The speed converter receives a 40-knot/ 
360, 60-hertz speed signal and, through the use 
of a servo system and gearing, repositions 
five synchro transmitters which then transmit 
10-knot/360, 40-knot/360, 100-knot/360 400- 
hertz; 10-knot/360, 100-knot/36060-hertz speed 
signals to equipment that requires them. Figure 
9-30 illustrates the speed converter in the 
underwater /dummy log system and shows the 
difference between typical Litton and Chesapeake 
systems. 

DEAD RECKONING 

SYSTEMS 

The dead reckoning systems provide a means 
of plotting the ship's position graphically on an 



REMOTE CONTROL UNIT 



CHESAPEAKE 
UNDERWATER 

LOG 
SYSTEM 



60 HERTZ DISTANCE 

60 HERTZ 40 K/360 SPEED 



60 HERTZ 100 K/360 SPEED 
400 HERTZ 10 K/360 SPEED f" 
400 HERTZ 40 K/360 SPEED 



TO SHIP'S EQUIPMENT 

AND 
REPEATERS 



400 HERTZ 100 K/360 SPEED J 




60 HERTZ 



SPEED AND 
DISTANCE 



I.C 

AGO - 
SWITCH 




60 HERTZ 




60 HERTZ 10 K/360 SPEED | 



60 HERTZ 100 K/360 SPEED 
400 HERTZ 10 K/360 SPEED > TO EQUIPMENT 



400 HERTZ 40 K/360 SPEED 



4OO HERTZ 100 K/360 SPEED J 



SPEED AND 
DISTANCE 



B 



60 HERTZ DISTANCE AND 
40 KNOT/360 6O HERTZ 
SPEED TO REPEATERS 
AND EQUIPMENT 



27.386 

Figure 9-30. Underwater and Dummy Log Installations: (A) Chesapeake, (B) Litton, including dummy 

log and speed converter. 



183 



SHIPBOARD ELECTRICAL SYSTEMS 



appropriate chart, plotting the ship's track, and 
plotting targets relative to the ship's position. 
Most dead reckoning systems also indicate the 
ship* s position in latitude and longitude on mechan- 
ical dials. 

There are several different types of dead 
reckoning equipment. In this section we shall 
discuss the Arma system, various NC-2 plotting 
systems, and the Mk 6 Mod 4B Dead Reckoning 
Tracer used in conjunction with the Mk 9 
Mod 4 Dead Reckoning Indicator Analyzer. 



ARMA DEAD RECKONING 
EQUIPMENT 

The Arma dead reckoning equipment (DRE) 
contains (1) a dead reckoning analyzer and 
(2) a dead reckoning tracer. A block diagram of 
the dead reckoning system is illustrated in 
figure 9-31. 



input from the ship's gyrocompass. The DRA 
using the ship's course input, resolves th 
ship's distance input into rotary E-W and N- 
distance components. This information is dis 
played on counters located inside the DRA an 
is transmitted by the d.c. step transmitters I 
the Arma dead reckoning tracer. 



Arma Dead Reckoning 
Tracer 

The dead reckoning tracer (DRT) (fig. 9-3; 
consists of (1) a tracking mechanism, (2) 
chart board that includes the pencil carriai 
assembly, and (3) an auxiliary plotting boar 
The auxiliary plotting board, which is the gla 
top of the DRT, is used for plotting ranges a 
bearings of contacts that are being tracked a 
for plotting own ship's position. The DRT 
housed in a metal case designed for horizonl 
mounting on a table or cabinet and is usua 
located in the combat information center. 



Arma Dead Reckoning 
Analyzer 

The dead reckoning analyzer (DRA) (fig. 
9-32) receives the ship's distance input from 
either the underwater or dummy log system. This 
input is in the form of a rotary motion, the rate 
of rotation being directly proportional to ship's 
speed. The DRA also receives the ship's course 



The tracking mechanism of the DRT contai 
the step-by-step receivers and gears that positi 
the pencil carrier assembly in response to 1 
E-W and N-S distance inputs from the DRA. The 
are two such receivers and gear trains 1 
cross screw drive assembly and the lead scr 
drive assembly. The cross screw and le 
screw drive assemblies position the pencil carr 
assembly along the axes shown in figure 9- 





OWN 
SHIPS COURSE 




N.S. 
DISTANCE 

.- .. -. - Jlllini 




MASTER 
GYRO- 
COMPASS 




DEAD 
RECKONING 
TRACER 




hit 


DEAD 
RECKONING 
ANALYZER 






E.W. 
DISTANCE 









OWN 

SHIP'S 
DISTANCE 




I, C. ACO 
SWITCH 



40. 



Figure 9-31. Dead reckoning system, block diagram. 

184 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



EAST MILES COUNTER TOTAL MILES COURSE SYNCHRO AND SHIP'S DISTANCE 

COUNTER \ FOLLOW-UP HEAD /SYNCHRO RECEIVER 



EAST STEP 
TRANSMITTER 




NORTH MILES 
COUNTER 

NORTH STEP 
TRANSMITTER 



COURSE 

FOLLOW-UP 

MOTOR 



40.57 



Figure 9-32 Arma dead reckoning analyzer 



By means of a switch either axis maybe selected 
to represent a N-S direction. That is, either 
the lead screw or cross screw drive assemblies 
in ay be actuated by the N-S or E-W distance 
input. Both drive assembly gear trains are 
adjustable and may be shifted to provide four 
different tracking scales so that 1 inch of move- 
ment by the pencil carriage assembly may 
represent from 200 yards to 16 miles of ship's 
movement. 

The chart board consists of a recessed 
plotting surface in the left-hand section of the 



DRT case below the pencil carriage assembly 
(fig. 9-33). A pencil, attached to the pencil 
carriage assembly, automatically traces the 
movements of the ship on a chart inserted on 
the plotting surface. 

The pencil carrier assembly is illustrated 
in figure 9-34. The pencil carrier assembly 
is supported by the pencil carriage assembly 
and includes the pencil, the pencil magnet, and 
the range-bearing projector. The pencil magnet 
is actuated by a clock-driven switch located 
with the tracer mechanism which energizes 



185 



SHIPBOABD ELECTRICAL SYSTEMS 



CLOCK- SWITCH 



TRACER MECHANISM 



RANGE- BEARING 
PROJECTOR ASSEMBLY 



LEAD SCREW 

DRIVE 

ASSEMBLY 



PENCIL CARRIAGE 
ASSEMBLY 



CHART 
BOARD 



CROSS 
SCREW 
DRIVE 
AXIS 



DEAD 

RECKON I MS- 
INDICATOR 



LEAD SCREW 
DRIVE AXIS 



CROSS SCREW 

DRIVE 

ASSEMBLY 



CROSS SCREW 
HAMDWHEEL 




Figure 9-33. Arma dead reckoning tracer and dead reckoning indicator. 



40.61(40 



the pencil-magnet circuit at predetermined inter- 
vals. This action causes the magnet to lift the 
pencil from the chart periodically to omit the 
trace to facilitate interpreting the plot. The 
range-bearing projector assembly (plotting light) 
is mounted on the pencil carrier for use in 
conjunction with the auxiliary plotting board 
to indicate the own ship's position at all times* 
It projects a polar diagram display on the 
underside of the auxiliary plotting board. This 
projected polar diagram is used to plot own 
ship's track, position, and the position of targets 
relative to the ship* 



Dead Reckoning Indicator 

The dead reckoning indicator (DRI) (fig. 9-3; 
is located with the tracking mechanism of t 
dead reckoning tracer. It consists of a dial ui 
assembly that includes the latitude motor (driv 
by N-S distance signal from DRA), the longitu 
motor (driven by E-W distance signal from DR^ 
and dialSo The latitude and longitude dial asset 
blies each consist of two concentric dials. T 
outer latitude and longitude dials are graduat 
in degrees, and the inner latitude and longitu 
dials are graduated in minutes. 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



RANGE -BEARING 
PROJECTOR 




QUICK-RELEASE 
OPERATING LEVER 



PENCIL- 



PENCIL CARRIER 
SUPPORTS 



40.62 

Figure 9- 34 - Pencil carrier and range-bearing 
projector assembly. 



NEW DESIGN DEAD 
RECKONING EQUIPMENT 

One of the Navy's newer dead reckoning equip- 
ment systems consist of the Dead Reckoning 



Analyzer Indicator (DRAI) such as the Mk 9 
Mod 4 (DRAI) and the Mk 6 Mod4B Dead Reckon- 
ing Tracer (DRT). Figure 9-35 is a block diagram 
of this equipment. 



Mk 9 Mod 4 DRAI 

The Mk 9 Mod 4 DRAI (fig. 9-36) is a hybrid 
analog/digital device which continuously com- 
putes, transmits, and displays principal naviga- 
tion inform ation. The DRAI accepts synchro 
information of own ship's speed from the ship's 
underwater log system and own ship's heading 
from the ship's gyrocompass sy stein .Information 
required for dead reckoning is calculated from 
these signals and displayed on the various dials 
and counters on the front of the DRAI. Some 
of the information is electrically transmitted 
to related shipboard equipment. Figure 9-35 
illustrates which information is displayed and 
transmitted by the Mk 9 Mod 4 DRAI. 

The DRAI is used aboard surface ships and 
submarines. It can drive up to four Mk 6 Mod 4B 
DRT's simultaneously. When properly maintained, 
the DRAI is much more accurate than the Arm a 
DRA. 



INPUTS 




FINE 



/COARSE 




lit 

en 
de 

* 

n- 





DRAI 
MK-9 MOD 4 




COARSE ^ 


LATITUDE 
^LONGITUDE 
VELOCITY N-S 
"VELOCITY E-W 

DISTANCE N-S ^ 




MK-6 MOD 4B 
ORT 




FINE 


COARSE ^ 


FINE ^ 


DISPLAYED OUTPUTS 


DISPLAYED OUTPUTS 


OWN SHIPS SPEED 
OWN SHIPS HEADING 
VELOCITY N-S 
VELOCITY E-W 
TOTAL OWN SHIPS 
DISTANCE TRAVELED 
DISTANCE 
TRAVELED N-S 
DISTANCE 
TRAVELED E-W 

LATITUDE 
LONGITUDE 


COARSE ^ 


LATITUDE 
LONGITUDE 
SHIP POSITION 


FINE > 


COARSE ^ "" 


FINE m 




DISTANCE E-W 









Figure 9-35. Block diagram of the Mk 9 Mod 4 DRAI and Mk 6 Mod 4B 

187 



40.56 (40D) 



SHIPBOARD ELECTRICAL SYSTEMS 




Figure 9-36. DRAI Mk 9 Mod 4 dead reckoning analyzer indicator. 



40.147(4 



Dead Reckoning Tracer 
Mk 6 Mod 4B 



The Mk 6 Mod 4B Dead Reckoning Tracer 
(DRT) (fig. 9-37) graphically records own ship's 
dead reckoning track and computes and displays 
own ship's latitude and longitude on counter s a 

The DRT operates automatically from input 
signals of distance north and distance east from 
the step transmitters in the DUAL The east 
and north distance inputs from the DRAI drives 
the lead and cross screw mechanisms which 
position the pencil carriage/projector assembly 
and record the ship's track. Latitude and longi- 
tude are also continuously computed from the 
two distance inputs and are displayed on counters. 
The Mk 6 Mod 4B DRT mechanisms are similar 
to, but more modern than, those of the Arm a 
DRT. 



NC-2 PLOTTING 
SYSTEMS 

The NC-2 plotting system was develo] 
primarily to aid Combat Information Cer 
watch personnel in plotting ship's position 
the position of contacts relative to own si 
The original system has been improved 
modified,, There are now several different N< 
plotting systems in use throughout the Ns 
Each of the systems usually consists of a I 
or a DRAI f and a plotting table. The ploti 
table serves the same purpose as the Ai 
DRT, plus being capable of displaying the loca' 
of from two to four targets relative to 
position of the ship. 

NC-2 Mod 

The NC-2 Mod (MARSLAND) was the origi 
plotting system. The system consists of th 



188 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 




Figure 9-37. Dead reckoning tracer Mark 6 Mod 4B 



40.6(40D)A 



major units the plotting table, a dead reckoning 
indicator, and a data converter (fig. 9-38). 
The plotting table houses three projectors, 
which are used for plotting the positions of own 
ship and two targets. The main projector assembly 
projects a polar diagram on the undersurface 
of the translucent table top. This polar diagram, 
the center of which represents own ship, moves 
in response to own ship's movements. Two 
smaller projectors, called target plot attach- 
ments (TPA's) project colored spots of light on 
the underside of the table top to represent the 
locations of the targets in relation to own ship* 
Each of the two TPA's projects a different 
colored spot of light one green, the other red 
so that the movement of the two targets may be 
followed with minimum confusion. Through the 
use of selector switches, either TPA may be 
controlled by range and bearing information from 



radar, sonar, fire control equipment, or other 
sources. 

The dead reckoning indicator provides a 
reading on a counter of the geographical position 
of the ship's latitude and longitude. Use of the 
dead reckoning indicator is optional. The re- 
mainder of the plotting system is independent 
of the dead reckoning indicator and may be 
used without it 

The data converter receives range and speed 
data from the ship's radar, sonar, fire control 
equipment, and underwater log equipment, and 
converts this data into a form usable by the 
plotting table* 

NC-2 Mod 1/1A 

The NC-2 Mod 1 (Sperry) consists of two 
major units: a bulkhead-mounted dead reckoning 



189 



SHIPBOARD ELECTRICAL SYSTEMS 



DEAD RECKONING INDICATOR 



MAIN CONTROL PANEL A6 




Figure 9-38. Plotting system Mk NC-2 



74, 



indicator (DRI) and a plotting table. The DRI ship's position and the position of as many 

employed in this system is an electromechanical four separate targets* As in the previous syste 

computer which computes latitude, longitude, own ship is represented by the center of 1 

and N-S and E-W speed from ship's gyro and polar diagram, and each target is represenl 

underwater log inputs The plotting table is by a different colored spot of Iight Each 

capable of providing a pictorial display of own the four TPA's may be controlled by inputs fr< 



190 



Chapter 9 SHIP'S INDICATING, ORDER, AND METERING SYSTEMS 



ship's radar, sonar or fire control equipment 
through a selector switch arrangement. 

The NO 2 Mod 1A (Sperry) system is a 
ruggedized version of the NC-2 Mod 1 system. 

NO 2 Mod 2/2A 

The NC-2 Mod 2/2A systems (Hartman) con- 
sist of two units each: (1) a dead reckoning 
analyzer indicator (DRAI) or a dead reckoning 
indicator (DRI), which computes own ship's dead 
reckoning position and (2) a plotting table, which 



displays own ship's position and the positions 
of four separate targets. 

The NC-2 Mod 2 and Mod 2A have identical 
plotting tables. The systems differ in that the 
Mod 2 is supplied with a Mk 8 DRI and the Mod 
2A is supplied with a Mk 9 Mod or Mk 9 Mod 2 
DRAI. Since the Mod 2A is the most common 
system used, we shall discuss its operation, 

MK 9 DEAD RECKONING ANALYZER 
INDICATOR. The Mk 9 Mod DRAI (fig, 9-39) 
is designed for direct bulkhead mounting and 




27,387 
Figure 9-39. ASW plotting system NC-2 Mod 2-A: (A) NC-2 Mod 2 Plotting Table, (B) Mk 9 Mod DRAI. 

191 



SHIPBOARD ELECTRICAL SYSTEMS 



can be operated as an independent unit or in 
conjunction with, and as a part of, the NC-2 
Mod 2A plotting system. When used with the 
NC-2 Mod 2A plotting system, the DRAI is 
electrically connected to the NC-2 Mod 2 plotting 
table , 

There are two versions of the DRAI used with 
the NC-2 Mod 2 plotter: the Mk 9 Mod DRAI, 
designated the standard unit; and the Mk 9 Mod 2 
DRAI, designated the low noise or "silent" 
unit. Only minor differences exist between the 
two versions. 

The DRAI is an electromechanical computer, 
employing digital circuits that receive inputs 
of own ship's speed (OSS) and own ship's course 
(OSC). From these inputs, the N-S and E-W 
components of ship's speed are computed for 
internal use within the DRAI and for trans- 
mission to external shipboard equipment. In 
addition, OSS is integrated with respect to time 
to give a counter readout of total distance 
traveledo 

The N-S and E-W speed components are 
also integrated to provide a counter readout 
of distance traveled in the N-S or E-W direction. 
The DRAI supplies a counter readout of ship's 
latitude and longitude, computed from the N-S 
and E-W components of ship's speed. The DRAI 
can transmit computed values of latitude, longi- 
tude, present ship's position in N-S and E-W 
components, own ship's speed N-S and E-W 
and change of position in N-S and E-W components. 

The Mk 9 DRAI is also capable of trans- 
mitting N-S and E-W distance information in a 
d.c. step form that may be used to drive the 
previously described Mk 6 Mod 4B DRT. 



PLOTTING TABLE NC-2 MOD 2. The NC-2 
Mod 2 plotting table, although more modern 
in design, essentially performs the same functions 
as the other plotting tables,, The plotting table 
is capable of graphically displaying own ship's 
position and four air, surface, or underwater 
targets on the plotting surface. 



PT-512/S Tactical Display 
Plotting Table (formerly 
NC-2 Mod 3) 

Unlike the other NC-2 systems, the PT-512/S 
tactical display plotting table consists of only 
one unit which is an upgraded version of the 
NC-2 Mod 2 plotting table. The components of 
the DRAI that were necessary to operate the 
plotting table have been relocated inside the 
plotting table, thus eliminating the necessity 
of the DRAI. The PT-512/S plotting table operates 
as the previously described plotting tables. It 
receives synchro speed and course data from the 
underwater log and gyrocompass and converts 
the data to analog signals which position the 
polar diagram. The four TPA's receive their 
inputs through a selector switch that enables 
the operator to select any of nine target range 
and bearing inputs. 

The PT-512/S tactical display plotting table 
provides a numerical readout of ship's speed 
and heading. The system doe snot provide displays 
of latitude or longitude, as do the other systems, 
The PT-512/S plotter produces d,c, step outputs 
that may be used to drive the Mk 6 Mod 4B DRT, 



192 



CHAPTER 10 

INTERIOR COMMUNICATIONS 
TELEPHONE SYSTEMS 



Telephones provide a rapid and efficient 
means of communication between the many sta- 
tions aboard ship. A satisfactory telephone system 
must be reliable; must not be susceptible to 
damage during battle; must be able to make 
rapid completion of calls; and must be easy 
to maintain. The sound-powered telephone fulfills 
these requirements. As the name implies, the 
sound-powered telephone requires no outside 
power supply for its operation. The sound waves 
produced by the speaker's voice provide the 
necessary energy to reproduce the voice at a 
remote location. 

In addition to sound-powered telephones, dial 
telephones are provided aboard some ships. 
The dial telephone system is used for adminis- 
trative purposes and is not depended on under 
battle conditions. 

SOUND-POWERED 
TELEPHONES 

The sound-powered transmitter (microphone) 
and receiver units in some sound-powered tele- 
phones are identical and interchangeable. Other 
telephones have sound-powered units that differ 
slightly The principle of operation, however, is 
the same for both the transmitter and receiver. 

As illustrated in figure 10-1 a unit consists 
of two permanent magnets, two pole pieces, 
an armature, a driving rod, a diaphragm, and a 
coil. The armature is located between four 
pole tips, one pair at each end of the armature. 
The spacing between the pole tips at each end 
is such that an air space remains after the 
armature is inserted between them. This air 
space has an intense magnetic field, which is 
supplied by the two magnets that are held in 
contact with the pole tips. 

The armature is clamped rigidly at one 
end near one of the pairs of poles and is con- 
nected at the other end to the diaphragm by the 
drive rod. Hence, any movement of the diaphragm 
causes the free end of the armature to move 



toward one of the pole pieces. The armature 
passes through the exact center of a coil of 
wire that is placed between the pole pieces 
in the magnetic field. 

The armature of a transmitter unit, when 
there are no sound waves striking the diaphragm, 
is shown in figure 10-1A Sound waves striking 
the diaphragm cause it to vibrate back and forth 
(fig. 10-1B and C). The armature bends first to 
one side and then to the other, causing an 
alternating polarizing flux to pass through it, 
first in one direction and then in the other. 
These lines of force passing through the arma- 
ture vary in strength and direction, depending 
on the vibrations of the diaphragm. This action 
induces an emf of varying direction and mag- 
nitude- that is, an alternating voltage in the 
coil. The alternating voltage has a frequency 
and waveform similar to the frequency and 
waveform of the sound wave striking the dia- 
phragm. 

When the coil of a transmitter unit (fig. 
10- 2A) is connected to the coil of a receiver 
unit (fig. 10-2B), the diaphragm of the receiver 
unit will vibrate in unison with the diaphragm of 
the transmitter unit and thus generate corre- 
sponding sound waves. 

The two types of sound-powered telephones 
installed aboard Navy ships are handsets and 
headsets. All telephones of a given type are 
built to the same military specifications regard" 
less of the manufacturer. 

HANDSETS 

The type H-203/U handset is designed for 
general use, primarily one-to-one talking. Tlie 
sound-powered transmitter and receiver units 
are interchangeable. SI, a nonlocking, normally 
open, spring-return push switch, (fig. 10-3) 
disconnects the sound-powered units from the 
line in the open position and connects the units 
to the line in the closed (depressed) position. 
Capacitor Cl is connected in parallel with the 
sound-powered units for tone compensation. 



193 



SHIPBOARD ELECTRICAL SYSTEMS 



MAGNET 





COIL 



ARMATURE 



B 



Figure 10-1.- Sound-powered transmitter receiver unit. 



27.28 




HEADSETS 



TRANSMITTER 

A 



RECEIVER 

B 



Figure 10-2. Operation of sound-powered units. 



27.28! 



The type H-200/U headset is designed for 
general use as well as for use with transistor- 
ized sound-powered telephone amplifiers. 

When a sound-powered telephone set is used 
on the output side of a sound-powered telephone 
amplifier, a small d.c. voltage is placed across 
the set to provide an amplifier squelching circuit 



to avoid acoustical feedback when the local se 
is transmitting. Capacitor Cl (fig. 10-4) prevent 
the flow of d.c. through the receiver units 
When the press-to-talk switch is depressed 
d.c. current flows through the transmitter uni 
causing a relay in the amplifier to operat 
and activate the squelching circuit. Capacito 
C2 provides power-factor correction and im 
proves the acoustical quality of the sound 
powered headset. The sound-powered transmitte 



194 



TWISTED PAIR 
LINE CORD 



SOUND-POWERED 
RECEIVER UNIT 




SOUND-POWERED 
''"TRANSMITTER 
UNIT 



Figure 10-3. Wiring diagram of a sound-powered telephone handset. 



and receiver units of headsets are not inter- SOUND-POWERED 

TELEPHONE SYSTEMS 
CIRCUITg 



3.198 



The type H-202/U headset is a specially 

designed set for use in areas that have high As classified by usage there are three types 

noisi levels. The receiver units are housed in of sound-powered telephone circuits: 
noise attenuating shells plastic caps lined with 

sound absorbing material. The sound-powered 1. The primary battle telephone circuits JA 

units are not interchangeable, to JZ (table 10-1) include all circuits used for 



RECEIVER 




RECEIVER 



140.33 



Figure 10-4. Wiring diagram of a sound-powered telephone headset. 

195 



SHIPBOARD ELECTRICAL SYSTEMS 



Table 10-1. Sound- Powered Telephone Circuits 



Circuit 



Primary Circuits 



Title 



JA 

JC 

10JC 

JD 

JF 

1JG 

2JG 

2JG1 

2JG2 

2JG3 

3JG 

4JG1 

4JG2 

4JG3 

5JG1 

5JG2 

6JG 

9JG 

10JG 

11JG 

JH 

JL 

JK 

JM 

JN 

JO 

2JP 

4JP 

5JP 

6JP 

8JP 

9JP 

10JP 



Captain's battle circuit 

Weapons control circuit 

Missile battery control circuit 

Target detectors circuit 

Flag officer's circuit 

Aircraft control circuit 

Aircraft information circuit 

Aircraft strike coordination circuit 

Aircraft strike requirement and reporting circuit 

Aircraft information circuit CATTC direct line 

Aircraft service circuit 

Aviation fuel and vehicular control circuit 

Aviation fueling circuit forward 

Aviation fueling circuit aft 

Aviation ordnance circuit 

Aviation missile circuit 

Arresting gear and barricade control circuit 

Aircraft handling circuit 

Airborne aircraft information circuit 

Optical landing system control circuit 

Switchboard cross connecting circuit 

Lookouts circuit 

Double purpose fuse circuit 

Mine control circuit 

Illumination control circuit 

Switchboard operators' circuit 

Dual purpose battery control circuit 

Heavy machine gun control circuit 

Light machine gun control circuit 

Torpedo control circuit 

ASW weapon control circuit 

Rocket battery control circuit 

Guided missile launcher control circuit 



27.337 



196 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



Table 10-1. Sound- Powered Telephone Circuits Continued 



Circuit 



Primary Circuits 



Title 



10JP1 

10JP2 

11JP 

JQ 

JR 

JS 

US 

2JS 

3JS 

20JS1 

20JS2 

20JS3 

20JS4 

21JS 

22JS 

23JS 

24JS 

25JS 

26JS 

31JS 

32JS 

33JS 

34JS 

35JS 

36JS 

61JS 

80JS 

81JS 

82JS 

JT 

1JV 

2JV 



Starboard launcher circuit 

Port launcher circuit 

FBM checkout and control circuit 

Double purpose sight setters circuit 

Debarkation control circuit 

Plotters' transfer switchboard circuit 

CIC information circuit 

NTDS coordinating circuit No. 1 

NTDS coordinating circuit No-. 2 

Evaluated radar infortxiation circuit 

Evaluator's circuit 

Radar control officer's circuit 

Weapons liaison officer's circuit 

Surface search radar circuit 

Long range air search radar circuit 

Medium range air search radar circuit 

Range height finder radar circuit 

AEW radar circuit 

Radar information circuit 

Track analyzer No. 1 air radar information check 

Track analyzer No. 2 air radar information check 

Track analyzer No. 3 air radar information check 

Track analyzer No. 4 air radar information check 

Raid air radar information circuit 

Combat air patrol air radar information circuit 

Sonar information circuit 

ECM plotters' circuit 

ECM information circuit 

Supplementary radio circuit 

Target designation control circuit 

Maneuvering and docking circuit 

Engineers' circuit (engines) 



27.3 



197 



SHIPBOARD ELECTRICAL SYSTEMS 



Table 10-1. Sound-Powered Telephone Circuits Continued 



Circuit 



Primary Circuits 



Title 



3JV 

4JV 

5JV 

6JV 

11JV 

JW 

JX 

2JZ 

3JZ 

4JZ 

5JZ 

6JZ 

7JZ 

8JZ 

9JZ 

10JZ 
11JZ 



Engineer's circuit (boiler) 

Engineer's circuit (fuel and stability) 

Engineer's circuit (electrical) 

Ballast control circuit 

Waste control circuit 

Ship control oearing circuit 

Radio and signals circuit 

Damage and stability control 

Main deck repair circuit 

Forward repair circuit 

After repair circuit 

Midships repair circuit 

Engineer's repair circuit 

Flight deck repair circuit 

Magazine sprinkling and ordnance repair circuit forward 

Magazine sprinkling and ordnance repair circuit aft 
Gallery deck and island repair circuit 

Auxiliary Circuits 



XJA 

X1JG 

X1JV 

XJX 

X2JZ 



Auxiliary captain's battle circuit 
Auxiliary aircraft control circuit 
Auxiliary maneuvering and docking circuit 
Auxiliary radio and signals circuit 
Auxiliary damage and stability control circuit 

Supplementary Circuits 



X1J 

X2J 

X3J 

X4J 

X5J 

X6J1 

X6J7 

X6J11-14 

X7J 



Ship administration circuit 
Leadsman and anchor control circuit 
Engineer watch officer's circuit 
Degaussing control circuit 
Machinery room control circuit 
Electronic service circuit 
ECM service circuit 
NTDS service circuits 
Radio-sonde information circuit 



27.331 



198 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



Table 10-1. Sound-Powered Telephone Circuits Continued 



Circuit 



Supplementary Circuits 



Title 



X8J 

X9J 

X10J 

X10J1 

X10J10 

XI 1J 

X12J 

X13J 

X14J 

XI 5 J 

XI 6 J 

XI 7 J 

XI 8 J 

XI 9 J 

X20J 

X21J 

X22J 

X23J 

X24J 

X25J 

X26J 

X28J 

X29J 

X34J 

X40J 

X41J 

X42J 

X43J 

X44J 

X45J 

X50J 

X61J 



Replenishment-at-sea circuit 

Radar trainer circuit 

Cargo transfer control circuit 

Cargo transfer circuit-Lower decks 

Cargo transfer circuit-Upper decks 

Captain's and admiral's cruising circuit 

Capstan control circuits 

Aircraft crane control circuits 

Missile handling and nuclear trunk crane circuit 

SINS information circuit 

Aircraft elevator circuit 

5-inch ammunition hoist circuit 

Machine gun ammunition hoist circuits 

Missile component elevator circuit 

Weapons elevator circuits 

Catapult circuit 

Catapult steam control circuit 

Stores conveyor circuit 

Cargo elevator circuit 

Sonar service circuit 

Jet engine test circuit 

Dumbwaiter circuit 

Timing and recording circuit 

Alignment cart service circuit 

Casualty communication circuit 

Special weapons shop service circuit 

Missile assembly and handling circuit 

Weapons system service circuit 

ASROC service circuit 

Special weapons security circuit 

Fog foam circuit 

Nuclear support facilities operations and handling circuit 



27.337 



from the wiring of the corresponding primary 
circuits to lessen the possibility of battle damage 
to both circuits. 

3. The supplementary telephone circuits X1J 
through X61J consist of circuits that provide 
communications for various administrative, 
service, and secondary control functions. 

The various sound-powered telephone systems 
are classified by construction into three groups; 
switchboard circuits, switchbox circuits, and 
string-type circuits. 



Switchboard Circuits 

A switchboard circuit (fig. 10-6) has the lino 
for each telephone station connected to an indi- 
vidual ewitchjaok. The ewitchjack (fig. 10-5A) 
le a combination line cutout switch and telephone 
jack. Each switohjack is mounted in rows on the 
switchboard (fig. 10-GB). The lino cutout switch 
portion of the swltchjack either connects or 
disconnects a telephone station from Its circuit. 
The Jack portion of the switohjack is usotl with 
a patching cord to either parallel tho telephone 
station associated with a particular Bwltchjack 
to another circuit or servos to pnrallul two 
entire circuits. 

Most largo combatant ships have eovoral 
sound-powered telephone switchboards installed 
in different centrally located and protected control 
stations. Bach switchboard usually has facilities 
to control several switchboard circuits. 





Switchbox Circuits 



A switchbox circuit has the line for oach 
telephone station connected to one of the Indi- 
vidual cutout switches which are mounted in a 
switchbox (fig. 10-6). Each cutout switch either 
connects or disconnects an individual telephone Figure lQ-5. 
station to a circuit. 

200 



2' 

Sound-power od telephone B 
and switchjack. 





27. 29 IX 
,ound~poworod telephone Bwilohbox. 



10 Bwltohoa nmy bo used as tlo 
:jctod to Uio circuit bus in other 
'hon Ihuuu llo HwlLuhuH tiro closed, 
i tho two l)oxoB arc paralleled, 
oro 1ft only ono nwllahbox for caoh 
,ono swltchboxoR function primarily 
) switchboards Tho awituhboxos 
Lho principal Htallon on tho circuit, 
hor 10 or 20 swllchua. 

IroullB 

pu circuit uoiislftlB of a eorloa 

station JriokboxoH connected In 
single Him. Thoro are no action 

for Individual HtaUona. 

casually communication clroull, 
Hot) H Htrln^-typu ulroulU con- 
dual rlKor unbluH ruuuliiK from 
jnglnuurinf"; HpauuB and Bluurlng 

four tffing JftckboxoH on Uio main 
u 10-7. 

ital runw aru ni.-ido an roqulrod 
irol partloH with rolls of oabloa, 
,o up on ruulB with i>lugB on onoh 



for 



ansfor switchboards (fig. 10-8) 
IGS arranged in a matrix form, 
jnt Bound-poworod jaokboxos and 
:onnootod to thoso ewllchboat'ds. 



140.187 



Figure 10-7, X40J circuit risers. 



As shown in figure 10-8B, the closing of any 
one of the five switches associated with each 
jaokbox permits the Jackbox to be connected 
to one of the sound-powered circuits. In figure 
10-8J3 jaokbox JS1 is shown connected to sound- 
poworod circuit 22JS, and jaokbox JS2 is shown 
connected to sound-powered circuit 81JS. Any 
of the remaining jaokboxes, JS3-JS10 may be 
connected to ono of the five sound-powered 
circuits by simply closing the associated switch, 

Plotters transfer switchboards are found in 
aroae aboard ship such as C1C ( whore the 
tactical situation governs the sound-powered 
circuit to which the plotters are to be connected. 
For Instance, the situation may require that the 
CIC plotters connected to jackboxos JS1- JS6 be 
'connected to circuit 21JS, while tho plotters 
connected to juckboxee JS6 - JS10 are connected 
to circuit 22JS. Another situation may call for 
another arrangement. The plotters transfer 
switchboard permits the plotters to be shifted 
from ono circuit to another quickly and effi- 
ciently ns tho situation dictates and eliminates 
tho necessity of Installing multiple circuit phone 
boxas at oaoii location. 



Selector Switches 

Selector switches (fig, 10-9) are located 
at tho most Important stations throughout the 
ship to enable the officer in charge, or his 
talker, to connect his telephone to any one of 
a group of circuits without having to change 
from ona Jaokbox outlet to another. 



SHIPBOARD ELECTRICAL SYSTEMS 



CIC SECT. 




JS-I 



LEGEND: 

H- INDICATES OPEN SWITCH 
-f INDICATES CLOSED SWITCH 

(A) 



INPU1 


CVJ 10 "3- 
CVJ <NJ <VI CNJ OO 


JACKBOX 


o 

T 




- A 


I 


































^ 


S.P. 
JACKBOX 


1 
















O 
















JS-2 

S.P. 
> JACKBOXES 
JS3-JS10 

CIRCUIT 81JS 
CIRCUIT 24JS 

CIRCUIT 23JS 
CIRCUIT 22JS 
riprniT 91 .ic 




















































































SP 
SP 

SP 
SP 
SP 














rc-fe 


#:::S 


^5::?:::: 


Mi^ 


iil^: 


j) 




















(B) 



Figure 1 0- 8 Plotters transfer switchboard. 



36.69 



SOUND- POWERED 

TELEPHONE 

CIRCUIT MAINTENANCE 



SOUND- POWERED 
TELEPHONE AMPLIFIER 
AM-2210/WTC 



Preventive maintenance for sound-powered 
telephone circuits consists of routine tests, 
inspections, and cleaning, which should be con- 
ducted in accordance with current PMS require- 
ments. Cleanliness is essential to the proper 
operation of sound-powered telephone equipment 
because of the low voltages and currents involved. 



In high noise-level areas such as engineering 
control, steering engine rooms, and gun mounts, 
it is often difficult, if not impossible, to hear 
sound-powered telephone conversations, even 
over the best maintained circuits. Recognizing 
this, the Navy developed the sound-powered 
telephone amplifier to assist communications 



202 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 




27.388 



Figure 10-9. Selector switch. 



in these vital areas. The transistorized AM- 
2210/WTC, presently in wide use throughout 
the fleet, meets the following requirements with 
a high degree of reliability: 

1. Amplifies one-way communications in a 
two-way sound-powered system using existing 
sound-powered headsets. (That is, it amplifies 
the voice to a gun mount but not the voice from 
it.) 

2. Supplies six outlet headsets and two loud- 
speakers. 

3. Is fail-safe on power loss or component 
failure. (Allows normal level conversation.) 

4. Operates on 115-volt 60-hertz a.c. power. 

When operating under normal conditions, the 
AM-2210/WTC (fig. 10-10) receives signals from 
a remote telephone line, amplifies them, and 
transmits the amplified signal to as many aa 
six local headsets and two loudspeakers. Direct 
talk-back between any of the six headsets and 
the remote line is carried out at normal sound- 
powered level, the amplifier being disconnected 




140.71 

Figure 10-10.- Sound-powered telephone amplifier 
AM-2210/WTC. 



upon actuation of any of the press- to- talk switches 
on any of the six local headsets. 

When the amplifier is deenergized or when 
certain predetermined casualties occur, the fail- 
safe feature permits direct two-way communi- 
cations between local and remote stations at 
a normal sound-powered level. 

Electrically the unit consists of an audio 
amplifier, a switching circuit, and a power 
supply. Equipment reliability is increased by 
the use of transistors in the audio and switching 
circuits. 

Although by no means trouble free, the AM- 
2210/WTC is a reliable unit. When trouble does 
occur, it often is caused by improper operating 
procedures or by a failure in external circuitry. 



CALL-BELL SYSTEMS 

Call-bell systems provide a means of signaling 
between stations in a ship. These systems consist 
of circuits E and A 

CIRCUIT E 

Circuit E provides a means of signaling 
between stations on sound-powered telephone 
circuits and outlets on voice tubes. Aboard 



203 



SHIPBOARD ELECTRICAL SYSTEMS 



large ships this circuit may be designated as 
follows: 

EM Self-contained circuits with m agneto 
call signal stations: Provides for selective calls 
over COMMON talk circuits. 

MJ Self-contained circuits with magneto call 
signal stations: Provides for selective calls over 
SELECTED talk circuits, 

EP Protected call circuits with cable runs 
protected behind armor. 

EPS Unprotected signal lines supplied from 
an EP circuit through separate protected fuses 
at the calling station. 

EPL- Unprotected circuits supplied from an 
EP circuit through a protected local cut-out 
switch at the station called. 

EX Exposed call circuits with cable runs 
not protected behind armor. 

In addition, circuit E has the following func- 
tional designations: 

IE Cruising and miscellaneous 

2E Ship control 

3E Engineering 

4E Aircraft control 

5E Fire control 

HE through 15E Turrets I through V 

For example, a circuit designated as 3EP 
is an engineering call-bell circuit with cables 
protected behind armor. 

Circuits EP and EX require an outside source 
of power and include bells, buzzers, or horns 
installed at selected sound-powered telephone 
stations and at some voice tubes* Watertight 
and nonwatertight pushbuttons, or spring return 
rotary switches, are provided at all signaling 
stations to complete circuits to the station 
called. Circuits EM and MJ are self-contained 
magneto-powered cell systems which utilize 1C /D 
call signal stations, normally called growlers 
or howlers (fig. 10-11). They are used in con- 
junction with sound-powered telephone systems. 



The call signal stations consist of a rotary 
selector switch, a hand-operated magneto gener- 
ator, and a howler unit. Selective calling of up 
to 16 individual stations is possible. When used 
in the circuit EM configuration, the sound- 
powered telephone and call systems are in- 
dependent of each other. In the MJ configuration 
the sound-powered telephone and call systems 
are combined. Through the use of a relay within 
the IC/D Call Signal Station, the sound-powered 
conversation is transmittedfrom station to station 
via the signaling leads. In the EM configuration 
only one conversation is possible at one time. 
With the MJ configuration up to 15 separate 
conversations are possible at one time. 

CIRCUIT A 

Circuit A is for the convenience of the ship's 
officers in callingpantry attendants and orderlies. 
Calls are provided from cabins, staterooms, and 
wardrooms to the respective pantries and order- 
lies. Circuit A calls are provided also from all 
sickbay berths and isolation wards to the attend- 
ant's desk in the sick bay. Circuit A consists 
of bells or buzzers at the orderly and pantry 
stations and nonwatertight pushbuttons in the 
various cabins, staterooms, and messrooms. 
Where a station is to be signaled by more than 
one pushbutton, a drop-type annunciator is in- 
stalled in addition to the bell or buzzer. 

A simplified call-bell circuit is shown in 
figure 10-12. This simplified circuit applies 
to circuit A as well as to circuit E. 

The upper branch circuit, with one bell and one 
pushbutton in series with each other, is used to 
call single station from one location. 

The center branch circuit, with two push- 
buttons in parallel with each other and in series 
with the bell, is used to operate one bell from 
two remote locations. 

The lower branch circuit, with two bells 
in parallel with each other and in series with one 
pushbutton, is used to operate two bells from 
one location. 

ANNUNCIATORS 

Stations (such as the bridge) that are served 
by several sound-powered circuits with their 
associated call-bell systems require some aid 
to distinguish between the sounds of the various 



204 



Chapter 10 -INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 




Figure 10-ll e IC/D call signal station. 



74.66X 



ignals. The need for this aid is especially 
ecessary when several magneto call stations 
re used because of the similarity of the sound 
ley emit. In addition, some means is needed 
r ith A call systems to aid in determining which 
tateroon) is signaling. Annunciators are used 
1th A and E call-bell systems to fulfill these 
eeds. 

Annunciators used with E call circuits are 
f the drop type. The drop, or target, is em- 
ossed with the designation of the sound-powered 
ircuit with which it is associated and is 
eld mechanically in the non-indicating posi- 
lon. When the circuit is energized (by 
pushbutton or by a turn of the crank of 
magneto call signal station at the calling 
tation), an electro-magnet causes the target 
D drop to the indicating position. The drops 
re returned to their normal, or nonindicating 
ositions by a hand-operated reset button. 



Annunciators used with A call circuits are 
similar to those used with E call circuits except, 
that in A call circuits, the drop is embossed 
with the number of the stateroom, or location 
of the calling station, instead of the circuit 
letter. 

An additional feature of annunciators is the 
ability to use a common audible signaling device 
controlled by relays in the annunciator. 



DIAL TELEPHONE 

SYSTEMS 

In addition to sound-powered telephone sys- 
tems, dial telephone systems are installed on 
the Navy's combatant ships. The dial telephone 
system, or circuit J, is primarily an adminis- 
trative circuit which provides complete selective 



SHIPBOARD ELECTRICAL SYSTEMS 



telephone communication throughout the ship 
The system is also used to supplement other 
communication facilities for ship control, fire 
control, and damage control. The capacity of 
the system varies with the size and needs of 
the particular ship. 

A dial telephone system consists of a group 
of telephones with lines so arranged at a central 
point that any two telephones in the system can 
be interconnected. In a dial telephone system, 
the connections between the telephones are com- 
pleted by remotely controlled switching mech- 
anisms. 

The switching mechanisms of a dial telephone 
system are controlled at the calling telephone 
by a dial on the telephone instrument. When the 
dial is operated, a series of interruptions, or 
impulses, occur in the current flowing in the 
line circuit. The number of impulses sent out 
by the dial corresponds to the digit dialed. These 
impulses cause the automatic switches to operate 
and to select the called telephone. 

A typical dial telephone system (fig. 10-13) 
consists of: telephone station equipment, made 
up of telephone instruments which may receive 
or initiate calls; dial telephone switchboard 
equipment that includes the switching necessary 
to interconnect the line stations; power equip- 
ment that furnishes normal and emergency power 
for the system; and accessory equipment used 
to interconnect the ship's telephone equipment 
with shore telephone equipment when the ship 
is in port. 



TELEPHONE STATION 
EQUIPMENT 



The telephone station equipment (sometimes 
referred to as line stations) consists of different 
types of telephone instruments. The telephone 
instrument is a unit which transmits and receives 
speech and signals the desired station. It 
comprises a transmitter, receiver, dial and 
ringer. The transmitter changes sound into an 
undulating current which is sent over anelectrical 
circuit. The receiver changes the undulating 
current back into sound. The dial, when operated, 
causes a series of interruptions (impulses) in the 
current flowing in the line circuit. The ringer 
provides an audible signal when the station is 
called. 



PUSHBUTTON 




27.292 



Figure 10-12. Simple call-bell system. 



Types of Telephones 

The types of telephones furnished with dial 
telephone systems are illustrated in figure 10-14 
The types differ mainly in the form in which 
the components are assembled. The components 
perform the same function, but the enclosure 
and method of mounting for each type is of 
special design. 

The TYPE A desk set telephone (fig. 10-1 4A) 
is installed in staterooms, cabins, offices, and 



206 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



TELEPHONE 

STATION 
EQUIPMENT 



SHORE LINES 



DIAL TELEPHONE 

SWITCHBOARD 

EQUIPMENT 



I 



ACCESSORY 
EQUIPMENT 



I 

1 I 
I I 
I L. 



POWER 
BOARD 



M~G 


SET 



BATTERY 



POWER EQUIPMENT 



J 



I 

| i SHIP'S POWER SUPPLY 

Figure 10-13. Block diagram of the dial telephone system. 



7.76(140B) 



similar stations. The desk set consists of a 
phenolic case (containing the ringer, dial and 
other working parts), a handset, and connecting 
cord with a terminal block for making the line 
connections. 

The TYPE F bulkhead telephone (fig. 10-14B) 
can be installed in any station except those on 
weather decks. The type F telephone is a non- 
watertight unit designed for mounting on a bulk- 
head or on the side of a desk. It consists 
essentially of a metal housing on which are 
mounted the handset, dial, and ringer. The line 
connections are made at a terminal block inside 
the housing. 

The TYPE C splashproof telephone (fig. 10- 
14C) is installed at stations on weather decks 
and at any other stations exposed to moisture. 
The type C telephone is designed for bulkhead 
mounting and consists essentially of a metal 
housing on which are mounted the handset and 
dial which axe enclosed in a splashproof box. 

The TYPE G telephone (fig. 10-14D) is used 
in all new dial telephone system installations 
and is used to replace the type A, C, and F 
telephone of older installations as they wear 
out. The basic type G telephone is available 
with three different enclosures which adapt it 
to use in place of the A, C or F telephones. 



DIAL TELEPHONE 

SWITCHBOARD 

EQUIPMENT 



The dial telephone switchboard is the switching 
center of the dial telephone system . Mounted in 
this switchboard are all telephone switching 
mechanisms, control circuits, part of the testing 
equipment, and most of the supervisory alarm 
signals. 

These switch mechanisms automatically per- 
form the following functions: 



1. Locate a station desiring to make a call. 

2. Respond to dial impulses and extend the 
calling station to the called station. 

3. Ring the called station and, if necessary, 
select between the two parties on a party line. 

4. Supply various tones, such as dial tone, 
busy tone, and ring-back tone, as required. 



At present there are at least four major 
types of dial telephone switchboard equipment 
employed in the Navy. In this section two of 
these types of equipment, the Automatic Electric 



207 



SHIPBOARD ELECTRICAL SYSTEMS 




A- TYPE A {DESK SET) TELEPHONE 




C-TYPE C {SPLASHPROOF) TELEPHONE 




6- TYPE F {BULKHEAD TYPE) TELEPHONE 



D-TYPE {G) BULKHEAD TELEPHONE 



Figure 10-14. Telephone station equipment. 



7.83 



208 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



and the Marine Dialmaster, plus their basic 
operating principles will be discussed. 



Automatic Electric 
Switchboard Equipment 



Until recently the Automatic Electric Switch- 
board equipment (figs. 10-15 and 10-16) was the 
only type employed aboard UJ3. Navy surface 
ships* This equipment was furnished in various 
sizes capable of servicing from 50 to more than 
600 telephone stations* The Automatic Electric 
Switchboard equipment utilizes the Strowger 
switch as the basic switching element to perform 
the functions required of a dial telephone switch- 
board. 



SWITCHING. The Strowger switch (fig. 10- 
17) is an electromechanical device which, as 
used in the Automatic Electric Telephone System, 
extends the connection from the calling to the 
called telephone. The assembly of fixed electrical 
contacts, arranged in ten levels, generally with 
ten sets of contacts to a level, is called a wire 
bank. The electrical members which make contact 
with the selected set of contacts in the wire 
banks are called wipers. These wipers are 
connected to the switch shaft. 



The switch mechanism elevates the shaft 
vertically (therefore the wipers) and then rotates 
the shaft (and wipers). Because of this vertical 
and rotary motion, the Strowger switch is often 
referred to as a two-motion switch. 



The Strowger switch is the basic switch of 
the system being used as a finder, connector, 
and selector, in each case employing slightly 
different electrical and mechanical variations. 
Figure 10-17 shows the mechanical elements 
common to all Strowger switches. As one of 
its variations, the finder switch has an additional 
set of vertical wipers connecting to a vertical 
bank. 



LINE GROUPING AND NUMBERING. The 
basic system of grouping provides for a maximum 
of 100 lines, as shown in figure 10-18. The 
horizontal dashes represent 100 pairs of metallic 
contacts* There are 10 horizontal levels and 



10 sets of contacts in each levelo Thus, the 
tens digit of the called number represents the 
level, whereas the units digit represents the 
individual pair of contacts in the leveL 

Numbers beginning with 1 are in the first, 
or bottom, level, numbers beginning with 2 
are in the second level, and so on. This arrange- 
ment causes the digit to be used to represent 
10 steps so that the 10th, or top, level is indicated 
by the symbol for zero. Also, the 10th pair of 
contacts in each level is indicated by the symbol 
for zero. Groups of 10 lines are referred to as 
lines 11-10, 21-20, 31-30, and so forth. The 
first 10 lines consist of 11-10, and the last 
10 consist of 01-00. 

Each pair of metallic contacts is connected 
to a pair of wires that lead to a particular 
telephone. These contacts are actually contained 
in a Strowger switch, arranged in the arc of a 
circle with the vertical rows parallel to the axis 
of the cylinder. The entire assembly of contacts 
is called a wire bank. 

These wire banks are commonly referred to 
by the type of switch with which they are asso- 
ciated, such as finder bank, connector bank, etc. 

A pair of metallic wipers mounted on the 
shaft of the Strowger switch is shown (fig 10-18) 
at the lower left-hand corner of the wire bank. 
These wipers are moved under the control of 
the dial on the calling telephone. For example, 
if the calling telephone calls telephone No. 32, 
when digit 3 is dialed, the wipers step UP to the 
third level in the wire bank. When digit 2 is 
dialed, the wipers rotate IN 2 steps on the 
third level to connect the calling telephone with 
telephone 32. Likewise, to connect the calling 
telephone with telephone 67, the wipers step UP 
6 steps and then rotate IN 7 steps. 



BASIC 100-LINE SYSTEM The system de- 
scribed with reference to figure 10-18 is not 
practical because only the calling telephone 
can originate calls Therefore, the basic 100-line 
system (fig. 10-19) was implemented. Each tele- 
phone is connected to the wipers of its own 
connector switch. The wiper of each switch can 
be stepped up and rotated in, under the control 
of the dial of the calling telephone. One connector 
bank with its wipers and the mechanism necessary 
to step the wipers up and in constitute a CON- 
NECTOR SWITCH, A connector switch is referred 



209 



SHIPBOARD ELECTRICAL SYSTEMS 



CONNECTOR SWITCHES 
1 5 



TEST- LINE JACK' 



CONNECTOR SWITCHES 
6-10 




AUXILIARY 
TEST PANEL 



CONNECTOR SWITCHES 
1115 



Figure 10-15. Connector cabinet, Automatic Electric Telephone Switchboard. 

210 



27.389 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



RINGING 
MACHINE NO. 1 



RINGING 
MACHINE NO. 2 



POWER 
CONTROL PANEL 



TERMINAL BLOCK 




RINGING 
MACHINE 
CONTINUE NO. 1 



RINGING MACHINE 

TRANSFER 8 
TEST SWITCHES 

RINGING 
MACHINE NO. 2 



TEST SET 



CONNECTOR 
TRUNK AND 
MISCELLANEOUS 
TERMINAL BLOCK 



27.390 



Figure 10-16. Automatic Electric Telephone Switchboard miscellaneous equipment cabinet. 



SHIPBOARD ELECTRICAL SYSTEMS 



VERTICAL MAGNET - 




SWITCH SHAFT 



VERTICAL BANK 



FOUND 
I ONLY ON 
( FINDER 

VERTICAL WIPER I SWITCHES 
WIPER CORDS 



WIRE BANK 



WIPERS 



Figure 10-17. Strowger switch. 



140.129 



to as a NUMERICAL type Strowger switch because 
it operates under the control of dial impulses. 

For simplicity, only 3 of the 100 telephones 
with their associated connector switches are 
shown in figure 10-19 

Telephone 32 is connected to the wipers of 
connector 32. Telephone 32 also has an appearance 
in the bank of each connector that is, it is 
multiplied to contact 32 in all of the connector 
banks. Telephone 67 terminates in wiper con- 
nector 67 and is likewise multiplied to its 
associated contact 67 in all of the connector 
banks. This multiple arrangement of the con- 
nector banks permits any telephone to call any 
other telephone in the system. 

For example, to call telephone 89 from 
telephone 32, remove the handset from the 
cradle at telephone 32 and dial the digits 8 and 
9. When 8 is dialed, the wipers of the connector 



switch 32 step up to the eighth level and when 
9 is dialed, the wipers rotate into the bank and 
come to rest on the ninth contact of that level. 
This action completes the connection to telephone 
89. 



LINE FINDINGo The 100-line connector 
system described with reference to figure 10-19 
requires an individual connector switch for each 
line in this system. As the connector is a 
relatively expensive switch, this system is not 
economical because the average telephone is used 
to make calls only a short time each day with 
the result that the corresponding connector switch 
remains idle during the remainder of the time. 

Line finding permits service to a large group 
of lines by a smaller number of switches used 
in common by all lines in the group. The line 
finding principle is illustrated in the diagram 
of the two switches shown in figure 10-20. 



212 



01 02 0.3 0405 06 07 08 09 00 



8828384858687888980 
71 7273747576T77879 70 



62 63 6465 66 ffi 68 69 60 



WIPERS 



7 58 59 50 






17 48 49 40 












57 38 39 30 






17 28 29 20 






7 18 19 10 




w 



CALLING 
TELEPHONE 



32) (67 
<~S \Ls 

TELEPHONES 



7,77(27C) 
Figure 10-18. Wire bank numbering* 



One is called the FINDER SWITCH and the other 
is the previously mentioned CONNECTOR 
SWITCH. One finder bank with its wipers and 
the mechanism necessary to step the wipers 
up and in constitute a FINDER SWITCH. A 
finder switch is referredtoasaNONNUMERJCAL 
type Strowger switch because its operation is 
automatic and not under the control of dial 
impulses. Although four telephones are shown, 
actually there are 100 telephones connected 
to the finder bank e 

To call telephone 00 from telephone 11, 
remove the handset from the cradle at 
telephone 11. The finder switch (fig, 
10-20) automatically steps its wipers up 
to the first level and rotates one step 
in, stopping on contact 11. Thus the 
calling telephone is extended through to 
the wipers of the connector switch. When 
the digits and are dialed, the 
wipers of the connector switch step up 
to the tenth level and rotate 10 steps 
in, completing the connection between tele- 
phones 11 and 00. 

BASIC 100 - LINE FINDER- CONNECTION 
SYSTEM. The system described with reference 




100 LINES 

TO 
100 TELEPHONES 



CONNECTOR 32 



WIPERS 



WIPERS 



CONNECTOR 67 



CONNECTOR S9 



WIPERS 



7.78(27C) 
Figure 10-19 Basic 100-line system. 



to figure 10-20 is equipped with one finder switch 
and one connector switcho Hence, only one con- 
versation is possible at any one time because 
each conversation requires one finder and one 
connector to complete and hold a connection 
between the calling and the called telephones. 

The 100-line finder-connector system is shown 
in figure 10- 21 A. Each finder switch is perma- 
nently tied stem to stern with a connector 
switch. In other words, the finder faces backward 
ready to find any line that originates a call, 
whereas the connector faces forward ready to 
connect to the dialed line. Such a combination 



213 



SHIPBOARD ELECTRICAL SYSTEMS 



TERMINALS- 



/ 



SHAFT 







rr 

^WIPE 


:R 


^ N 10 






i'' ^ x ^" 
















FINDER SWITCH 



PONNECTOR SWITCH 



Figure 10-20. Basic 100-line finder-connector system. 



7.78(140B) 



of finder and connector is called a FINDER- 
CONNECTOR LINK. One finder-connector link 
is required for each of the conversations that 
are to be held simultaneously* There are 15 
finder-connector links in the 100-line Automatic 
Electric Telephone System. 

Each of the 100 lines is connected to each 
finder bank. Hence, any idle finder is capable 
of stepping up and rotating in to locate any one 
of the 100 lines that originates a call. Also, 
each of the 100 lines is connected to each 
connector wire bank. Hence, under control of 
dial impulses from the calling telephone, the 
connector can step up and rotate in to complete 
a connection to any one of the 100 telephones. 

Look again at figure 10-21A* To call tele- 
phone 89 from telephone 32, remove the handset 
from the cradle at telephone 32. An idle finder 
such as finder 1, steps up, rotates in, and stops 
on contact 32. The connection is now extended 
through to the connector associated with the 
finder, in this case connector 1, and the dial 
tone is received by the calling telephone. The 
DIAL TONE is a signal to the person making 
the call to dial the number of the called tele- 
phone. When digits 8 and 9 are dialed, the wipers 
of the connector switch step up, rotate in, and 
stop on contact 89. 



The connection is now completed from tele- 
phone 32 through finder-connector link 1 to tele- 
phone 89 . The connector switch now te sts telephone 
89 and, if it is not in use, ringing current is sent 
out to operate the ringer at telephone 89. If 
telephone 89 is in use, a busy signal is returned 
to the calling telephone. 

A complete 100-line finder-connector system 
is shown in figure 10-21B, The finder and con- 
nector banks are each represented by 10 horizontal 
lines. The rectangles at the top of the finder and 
connector banks represent the switch mech- 
anisms. One line relay is associated with each 
line, whereas the finder control and the dis- 
tributor equipment is common to all lines a 

To call telephone 67 from telephone 32, 
remove the handset from the cradle at telephone 
32 This action closes contacts within telephone 
32 which causes line relay 32 to operate. Line 
relay 32 in operating marks the position of 
line 32 in the finder banks. 

When the line relay operates, it also sends 
a START SIGNAL to the finder control and 
distributor equipment which, in turn, starts apre- 
selected idle finder in search of the calling 
line. 

The finder control and distributor equipment 
at this time automatically preselects the next 



214 



Chapter 10 -INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



iES 



)NES 

v- 








r 






r 


t: 


)- 


r 



< 


FINDER 1 






TX 
< C 


DNNECTOR 


1 




















I 






> 





























:J 






























r 


FINDER 2 






r c 


ONNECTOR 


2 











































!> 






* * 




















* 


. ^ 



















* 









< 






^i 
























r 


FINDER 3 






jf r 


ONNECTOR 


3 

















MULTIPLED TO OTHER FINDER-CONNECTOR LINKS AS 
REQUIRED 

(A) 



N6 
DNE 


FINDER 
CONTROL 
AND 
DISTRIBUTOR 




CALLED 
TELEPHONE 

(6?) 


- FINDER] [CONNECTOR 




= 




LINE 


KULAK 041 



7. 80 (140 A) 

re 10-21. Complete 100-line finder- 
connector system. 



finder to have it ready to search for the 
incoming call. 

'he selected finder that is searching for line 
Lnds it and extends the connections through 
e connector switch. 



Line relay 32 in operating also makes line 
32 busy at the connector banks to guard against 
intrusion from any incoming call. 

The connector switch returns a dial tone 
to the calling telephone and the call proceeds 
as previously explained. 



EXPANDING THE 100-LINE SYSTEM, The 
100-line finder-connector system can be expanded 
to service as many as 200 telephones through the 
use of a party line system, made possible 
through the use of an additional switch called 
a minor switch. The minor switch has rotary 
motion only and is mounted with the connector 
switching mechanism. As pictured in figure 
10-22 the minor switch bank consists of 10 
sets of contacts over which the wipers may 
step under control of the dial. This switch is 
a one-function auxiliary switch which rings one 
or the other of two telephone stations on a two- 
party line. 

With the minor switch arrangement an ad- 
ditional digit is added to all phone numbers. In 
this type equipment, telephones having the first 
digit of 1, 2, 3, 4, 5, 6, 7, 8, or will receive 
ring current over their positive line, while those 
whose first digit is 9 will receive ring current 
over their negative line. The arrangementpermits 
the selective ringing of either telephone station 
of a two-party line. As an example, if you dial 
number 932, the ringer at telephone station 
932, which is connected to operate with negative 
ring voltage, will operate. The ringer at telephone 
station 232, which is on the party line with 
telephone station 932, will not operate because it 
is connected to operate on positive ringing voltage. 

BASIC FINDER-SELECTOR-CONNECTION. 
The system described with reference to figure 
10-21 has a capacity of 100 lines. In systems 
of 200 lines or more, a SELECTOR SWITCH 
is connected between the finder and connector 
switches, as shown in figure 10-23. The selector 
is similar in mechanical construction to both 
the finder and connector. It has a wire bank, 
wipers, and a two-motion switch mechanism. 

The selector faces the called line the same 
as does the' connector. The selector selects the 
"hundreds" group of lines. From then on, a 
connector selects both the "tens" group of 
lines and the "units" line in that group. Note 
that the lines (fig. 10-23) are divided into groups 



SHIPBOARD ELECTRICAL SYSTEMS 





ROTARY 
MAGNET 




RELEASE 
MAGNET 





ROTARY ARMATURE 
RESTORING SPRING 



BANK CONTACT 
TERMINAL 



OFF NORMAL 

SPRING 
ASSEMBLY 




WIPER ASSEMBLY 
RESTORING SPRING 



RELEASE ARMATURE 
RESTORING SPRING 



Figure 10-22. Minor switch. 



140.76 



of lOOo Two such groups are shown, the 200 
group with 100 lines and the 600 group with 
100 lines. Each group has a corresponding group 
of connectors which have their banks multiplied 
together. 

Note that each finder switch is tied stem to 
stern with a selector switch instead of being 
tied to a connector switch, as in the 100-line 



capacity system,, One finder-selector-connector 
link is required for each conversation that is 
to be held simultaneously with other conver- 
sations. The connector switch always operates last 
and selects the "tens" group of lines and the 
* 'units" line within the group. 

To call telephone 673, remove the handset 
from the cradle at the calling telephone. An idle 



216 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 










CONNECTOR 








GROUP 








^ 





















WORM WHEEL 



AC END 




100 TELEPHONES 

IN THE 
"600" GROUP 



100 TELEPHONES 

IN THE 
"200" GROUP 



7.82(27C) 
Figure 10-23. Basic selector system,, 



finder searches and extends the calling line to 
the selector switch associated with that finder. 
The selector returns a dial tone to the calling 
telephone. When the "hundreds" /digit 6isdialed f 
the selector wipers step to the sixth level and 
automatically rotates in to a contact that is 
attached to an idle connector; this extends the 
call through to the wipers of a connector. When 
digits 7 and 3 are dialed, the connector steps up 
7 levels and rotates in three steps to complete 
the call. 

ALARM SYSTEM. The Automatic Electric 
Dial Telephone switchboard contains an alarm 
system which warns watch personnel when con- 
ditions within the switchboard are not normal. 
The alarm system consists of a common audible 
buzzer and lamps that provide a visual indication. 
Alarms sound if power is lost, if fuses are blown* 
if problems develop within finder sand connector s, 
or if the handset of telephone stations are left 
off the hooko Conditions which cause the last two 
alarms listed usually result in the loss of a 
finder-connector link which limits the number of 
simultaneous conversations that the switchboard 
is capable of handling. 

Watch personnel should be alert to immediately 
correct the conditions that cause an alarm. 

RINGING MACHINES. The Automatic Elec- 
tric Dial Telephone switchboard contains two 
ringing machines (fig, 10-24) 9 which are small 
motor-generator sets. These motor-generator 
sets produce dial tone* busy tone, and ring and 
ring-back voltages for the dial telephone system* 
The second ringing machine provides a backup 
if the first machine fails P 



TERMINAL 
STRIPS 




WORM 



DC END 



FILTERS 



140.82 
Figure 10-24 Ringing machine (covers removed). 



POWER EQUIPMENT The power equipment 
includes a motor-generator set (fig. 10-25) and a 
storage battery The motor-generator set and the 
storage battery are connected in parallel and 
supply approximately 51 6- volt d.c. power to 
operate the automatic switchboard equipment, 
including the ringing machine sand alarm systems. 
The motor-generator set receives operating 
power from the ship's 440-volt 60-Hz, 3-phase 
power supply via the nearest 1C switchboard. 
A reserve supply of energy is maintained in 
the storage battery so that the telephone system 
will continue to operate if the ship's power 
supply fails. 

ACCESSORY EQUIPMENT. The accessory 
equipment (furnished in some ships) includes 
an attendant's cabinet (fig. 10-26) which is a 
small manual switchboard. The attendant's cabi- 
net provides an interface between the ship's 
telephone system and another telephone system 
to accomplish calls to and from shore exchanges 
when the ship is in port, and calls between 
ships when they are nested. 

MARINE DIALMASTER 
DIAL TELEPHONE 
SWITCHBOARD EQUIPMENT 

The Marine Dialm aster dial telephone switch- 
board equipment is a relatively recent develop- 
ment. The equipment is modular in construction 



217 



SHIPBOARD ELECTRICAL SYSTEMS 



FILTERS 



INPUT TERMINALS 



OUTPUT TERMINALS 



MOTOR 
LEADS 




SHUNT 

RESISTOR 

COMPARTMENT 



Figure 10-25. Motor-generator set (cover opened). 



140.87 



and it is much more compact than the previously 
discussed Automatic Electric Dial Telephone 
equipment. For example: the Marine Dialm aster 
100-line dial telephone system occupies less than 
half the space required for an Automatic Elec- 
tric system with the same capabilities. The 
compactness of the system is due to modular 
construction techniques. All electromechanical 
switching devices and solid-state circuits, as 
well as all power equipment, are mounted on a 
single equipment rack. The Marine Dialm aster 
dial telephone equipment is furnished in two 
basic systems. One system, the MDM/700, is 
furnished as a 200-line system capable of being 
expanded in 100-line increments to a maximum 
of 700 lines. The other system, the MDM/100- 
15, is a 100-line system which will be discussed 
as a comparison to the previously described 
Automatic Electric 100-line system. 

The MDM/100-15 dial telephone system per- 
forms the same basic function as the previously 
described Automatic Electric System. The pri- 
mary difference is that the MDM/100-15 system 
employs XY-Universal switches to perform the 
functions that the Strowger switch performs 
in the Automatic Electric System. The system 
is comprised of one switchboard cabinet and in 
some cases an attendant's cabinet. The MDM/ 
100-15 system can be used with the type A, 
C, F, or G telephone station equipment. 



MDM/100-15 
Switchboard 



The switchboard consists of one rack of 
equipment shock-mounted in a rigid cabinet 
assembly. The cabinet circuit modules, which 
are accessible through front and rear doors, 
plug into the frame-jack panel and contain all 
the switching circuits necessary to operate the 
system . Two XY-Universal switches are asso- 
ciated with each of the 15 link circuit modules. 
These switches are mounted in cells on the 
front of the frame, and they plug into the asso- 
ciated link circuit modules (fig. 10-27). The 
line connection panels, mounted directly on the 
switchboard frame (fig. 10-28), provide the means 
to connect the switchboard to the ship's telephone 
station cables. 



SWITCH COMPONENTS, In the MDM/100-15 
system, the XY-Universal switch (fig. 10-29) 
functions as a finder and as a connector and 
provides the means to establish connections 
from the calling telephone station to the called 
telephone station. The XY-Universal switch is 
a two-motion, remote-control device which may 
be operated under the control of a dial or auto- 
matically pulsed from associated control cir- 
cuitry. 



218 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



SHORE TRUNKS 

AND 

TERMINAL 
BLOCK 



OO'QOOQ.O 



KEY 

PANEL 



HEADSET 
RECEPTACLE 



LOCAL TRUNKS, 
FUSE PANEL, 

AND 

TERMINAL 
BLOCK 




Figure 10-26. Attendant's cabinet. 
219 



140.79 



SHIPBOARD ELECTRICAL SYSTEMS 



LINK CIRCUIT 
MODULE 



LINK ALLOTTER 
CIRCUIT MODULE 

LEVEL DETECTOR 
CIRCUIT MODULE 

COMMON CONTROL 
CIRCUIT MODULE 




FINDER XY SWITCH 
CONNECTOR XY SWITCH 
FINDER XY SWITCH 
CONNECTOR XY SWITCH 



XY SWITCH 
RETAINING DOOR 



MONITOR AND 
DISTRIBUTION PANEL 
CIRCUIT MODULE 



POWER SUPPLY 
CIRCUIT MODULE 



RING VOLTAGE 
GENERATOR 
CIRCUIT MODULE 



Figure 10-27. MDM/100-15 switchboard cabinet, front view. 

220 



27.391X 



Chapter 10 -INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



SHIP LINE MODULES 



WIRE CHANNEL 



CONNECTION PANEL 



POWER SUPPLY 
CIRCUIT MODULE 



RING VOLTAGE 

GENERATOR 

CIRCUIT MODULE 



SHORE TRUNK MODULES 

CONTROL MODULE, 




LINE CONNECTION 
PANELS 



CABLE ACCESS 
CHANNEL 



REAR JACK 
PANEL 

Figure 10- 28 , Switchboard cabinet, rear view. 
221 



SHIP'S CABLE 
ENTRY PANEL 



27.392X 



SHIPBOARD ELECTRICAL SYSTEMS 



P1U6 



RELEASE MAGNET 

X MAGNET 



XX-X WIPERS 



TtR,S t HS 
WIPERS 




Y MAGNET 

X CARRIAGE 
Y CARRIAGE 



Figure 10-29. XY-Universal switch. 



140.165 



The XY-Universal switch can make electrical 
contact with any of 100 sets of contacts, taking 
two motions to accomplish the connection. The 
switch is mounted in a horizontal plane. The 
switch carriage moves first in the X-direction 
(left to right parallel to the wire bank) and then 
in the Y-direction (into the wire bank). When 
mounted in the switchboard, the XY-Universal 
switch is located adjacent to a wire matrix, 
or wire bank. The wire bank runs the length 
of the switchboard and serves as the contacts 
for the wipers of all 30 XY-Universal switches 
in the system. 



The XY-Universal Switch. The main com- 
ponents of the XY-Universal switch (fig. 10-29) 



are an X- stepping magnet, a Y- stepping magnet, 
a release magnet, spring pileups, and associated 
mechanical drive hardware. The switch steps 
first in the X-direction, controlled by a series 
of pulses extended to the X-stepping magnet. 
Each time the magnet operates, the wipers 
advance one step in the X-direction. The Y- 
stepping magnet functions in a similar manner 
to drive the wipers in the Y-directioft, which is 
into the wire bank. 

There are 30 XY-Universal switches used 
in the MDM/100-15 system, 15 as finders and 
15 as connectors. 

The Wire Bank. The wire bank associated 
with the XY-Universal switch is actually made 



222 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



up of six smaller wire banks: four 10 by 10 
wire banks and two 1 by 10 wire banks. The 
10 by 10 wire banks are used with the four 
wires associated with each telephone line. These 
four wires are the tip (T) and ring (R) for 
transmission, and the sleeve (S) and helping 
sleeve (HS) for supervisory and switching. The 
1- and 10-wire banks (XX and X) indicate elec- 
trically the X-position of the wipers when the 
wipers are stepped in the X-direction. Each 
of these banks is associated with its own par- 
ticular wiper on the XY-Universal switch; hence, 
the switch wipers are referred to as the T, 
R, S, HS, and XX-X wipers or banks. Figure 
10-30 is a simplified diagram of a 10 by 10 
wire bank (as seen from above) with its asso- 
ciated wiper. 

The wire banks run the length of the switch- 
board and are associated with the same wiper 
for each of the other 30 XY-Universal switches 
in the system (fig. 10-31). The X-motion of the 
switch locates the wiper at a position (or bank) 
opposite the proper section of the wire bank. 
The Y-motion of the switch positions the wiper 
into the bank to establish the connection at the 
proper point* 





20 


30 40 


50 


60 


70 80 


90 








100 


O 





O 


O 





O 


O 


O 


00 




190 


O 








O 


O 


o 


O 


o 


09 




180 











O 


O 





O 


o 


08 




170 





O O 


O 


O 


O 


o 


O 


o 


07 




160 








O 


O 


O 


o 


O 


o 


06 




150 


o 


o *> 


O 


O 


O 


o 


O 


005 


WIPER 


140 


o 


JO 








O 





O 


O 


04 


IN POSITION 
5 OF LEVEL 4 


130 





o 4 





O 


O 


O 





O 


o 


03 


STATION 45 


120 


o 


o 


o 





O 


O 


o 





o 


02 




11 





o 


o 


O 


o 


o 


o 


o 


o 


01 




V 


21 


31 


41 
\ 


51 


61 


71 


81 


91 








I 






U WIPER 


AFTER 


1st 


SET OF 


IMPULSES - 


K 


hk. 




1 DRIVEN TO POSITION 4 



-WIPER IN ORIGINAL (NORMAL) POSITION 
NOTE: DIRECTION OF WIPER MOVEMENT INDICATED BY *> 

140.167 

Figure 10-30. Wire bank and associated XY- 
Universal switch wiper, simplified diagram. 



FINDER-CONNECTOR LINKS. As previ- 
ously stated, the MDM/100-15 system contains 
30 XY- switches, 15 as finders and 15 as con- 
nectors. These finders and connectors are con- 
nected back to back, the same as the finders 
and connectors of the Automatic Electric System, 
through 15 link circuit modules as shown in 
figure 10-27. The link circuit module ties the 
linefinder and connector together and pro- 
vides control functions for both switches. The 
linefinder XY-Universal switch, connector XY- 
Universal switch, line circuit module, and their 
portion of the common wire bank comprise one 
finder-connector link. 



Link Allotter.- The link allotter performs 
the same function in the MDM/100-15 as the 
finder distributor of the Automatic Electric 
System assigns the next idle finder-connector 
link to the calling party. 



System Operation 



Basically, the operation of the MDM/100-15 
is very similar to that of the Automatic Electric 
System. Assume that telephone station 12 initiates 
a call to telephone station 95. When the calling 
telephone's handset is removed from the hook- 
switch of telephone 12, a signal is produced 
that causes the allotter to assign an idle finder- 
connector link to the calling telephone. As soon 
as an idle link is assigned, the finder of that 
link begins to search for the calling telephone 
line. In this case the finder XY-Universal switch 
will move 1 step in the X-direction and 2 steps 
in the Y-direction and the dial tone will return 
to the calling telephone station at this time. 
The number of digits that the calling party 
must dial depends on whether the system is set 
up to provide party line ringing (negative and 
positive ringing voltage). If party ringing is 
to be used, three digits are required, if not, 
only two digits are required. Let us assume 
that we are calling telephone 95 and that party 
ringing will not be used. Therefore, it is 
necessary to dial only two digits to reach the 
called telephone station. When the digits 9 and 
5 are dialed at the calling telephone, the con- 
nector XY-Universal switch steps 9 spaces in 
the X-direction and 5 spaces in the Y-direction. 
A busy test is then performed on line 95. If 
the line is busy, the busy tone will be returned 
to the calling telephone station. If the line is 



223 



SHIPBOARD ELECTRICAL SYSTEMS 



DUST COVER 



X-XX BANK 



TAND R 
BANK 



S AND HS 
BANK 




SWITCH 
CELL 



SWITCH 

CELL 

DOOR 



Figure 10-31. XY-Uni versa! switch cell and wire banks* 



140.168 



not busy, ringing will be extended to signal the 
called party. 



Power and Signaling 
Equipment 



The MDM/100-15 utilizes solid-state devices 
to provide its d.c, and ringing voltages. These 
devices are contained within the switchboard 
cabinet* 



Attendant's Cabinet 

The MDM/100-15 installations may be 
equipped with attendant's switching circuitry 



to provide attendant-assisted ship-to-shore com- 
munications. This circuitry is mounted in the 
switchboard cabinet (fig. 10-28) and consists 
of four ship line modules (one for each ship 
line), four shore line modules (one for each 
shore line), and one control module. The 
attendant's switching circuit is controlled from 
a remotely located attendant's cabinet (fig. 10-32). 
Since all of the attendant's switching equip- 
ment is mounted in the switchboard cabinet, 
the attendant's cabinet performs only the func- 
tions of a standard telephone with pushbutton 
control of switching modules to seize and inter- 
connect ship lines and shore lines. The attendant's 
cabinet is not much larger than a standard 
type-G telephone set and can be mounted on 
a desk or bulkhead, or flush-mounted in a 
suitable panel* 



224 



Chapter 10 INTERIOR COMMUNICATIONS TELEPHONE SYSTEMS 



> 

oo> o 




140.164 



Figure 10-32. Attendant's cabinet. 



PES OF CALLS 



Most of the shipboard dial telephone systems 
'e designed to permit a wide variety of tele- 
x>ne calls to meet a variety of needs. These 
pes of calls are summarized below. 

Regular local service is the routine call 
lerein the caller dials the desired number and 
iceives either a ring-back or a busy tone in 
s receiver. If the called station is manned 
id if the phone is not in use, the call should be 
mpletedo If a busy tone is received, the calling 
tone must redial the number. 

Executive service is that additional feature 
' which a priority telephone will cut in on a 
innection which has already been made to the 
inber which he wishes to reach. An executive 
tone always reaches the party called, even when 
e line is busy. 

Emergency service is a specifically designed 
ature by which any caller, who dials a special 
imber (usually 211), will reach the station at 



which the Officer of the Deck has posted his 
watch, whether the Quarterdeck or the Pilot- 
house. The call will be completed regardless of 
whether the line is open or busy. A switch con- 
trolling the recipient phone (Quarterdeck or 
Pilothouse) is located on the telephone switch- 
board. 

Ship to Shore Call is a call connected man- 
ually through the attendant's cabinet. To complete 
this call (possible only when in port and con- 
nected), the caller dials the attendant's cabinet, 
and the ship's operator extends the call through 
to the shore facility. 

Shore to Ship Call is also a feature conducted 
through the attendant's cabinet. Here again, the 
ship's operator completes the call through the 
manual facilities available to him at his station. 
On many installations ship's telephone lines 
37, 38, 39, and 30 are reserved for the manual 
switchboard. 

Additionally, the ' 'hunt the not-busy feature" 
is employed in cases where a series of numbers 
serve the same location. In this type arrangement, 
as in the case of the attendant's cabir^pt, assume 
that line 37 is in use and a second caller dials 
the attendant's cabinet number 37. The call will 
be shifted automatically to line 38. This "hunt" 
feature continues until the call is completed 
or until the caller receives busy from the last 
in the series of so connected lines (30). 

SAFETY 

Potentials as high as 450 VAC may be en- 
countered while your men work on dial telephone 
equipment. Your men must practice all standard 
precautions when working around high voltages, 
rotating machinery, and batteries. 

An additional precaution for dial telephone 
systems that you should observe is that all 
shore telephone lines must be connected to a 
lightning arrestor box located on the weather 
decks before the line is routed to the telephone 
equipment. The lightning arrestor boxprotects the 
telephone operator and the telephone equipment 
in case lightning should strike the incoming 
telephone lines. 

DIAL TELEPHONE 

SYSTEM MAINTENANCE 

Aboard ship, every attempt should be made 
to maintain a telephone school graduate with 
an NEC for the type of system installed. However, 
this is not always possible and should not be used 
as an excuse to let the system deteriorate. 




SHIPBOARD ELECTRICAL SYSTEMS 



The knowledge necessary to operate and 
maintain this sy stein can be obtained from a 
combination of PQS, OJT, and the manufacturer's 
technical manual. 

Dial telephone system maintenance includes 
periodic tests and inspections, lubrication, clean- 
ing, troubleshooting, and repair. Test equipment, 
special tools, special lubricants, and charts 
are provided with each system, and detailed 
maintenance instructions are included in PMS 
and the manufacturer's technical manual. 



Cleanliness is essential because of the low 
voltages and currents involved. Dirt and dust 
can cause insulation failures and high resistance 
or partially open contacts. 

The adjustable parts of the relay sand switches 
are delicate and require the use of special adjust- 
ment tools. Adjustment of a switch or relay 
should not be attempted until it has been definitely 
determined that adjustment is necessary. When 
adjustment is necessary, the manufacturer's 
instructions must be followed carefully* 



226 



CHAPTER 11 

AMPLIFIED VOICE SYSTEMS 



Many types of voice communication facilities 
are needed to effectively control and administer 
a naval vessel during the course of each day. 
The telephone systems, described in the previous 
chapters, fulfill many of these needs, but their 
effectiveness is limited in high noise level areas 
and where it is desired to transmit a command 
or information to several listeners simultan- 
eously. Amplified voice systems are used to 
overcome some of the shortcomings of telephone 
systems. 

Amplified voice systems are used in a wide 
variety of forms aboard Navy ships such as 
public address and intercommunication (inter- 
com) systems. Other variations of amplified 
voice systems that are employed are tape re- 
corders, sound motion picture projection equip- 
ment, and ship's entertainment equipment. 



ANNOUNCING AND 

INTERCOMMUNICATING 

SYSTEMS 

The general purpose of shipboard announcing 
and intercom systems, circuits IMC through 
59MC, is to transmit orders and information 
between stations within the ship by amplified 
voice communication by either a central ampli- 
fier system, or an intercommunication system. 
A central amplifier system is used to broadcast 
orders or information simultaneously to a number 
of stations. An intercom system is used for 
two-way transmission of orders or information. 

Each announcing and intercom system in- 
stalled aboard ship is assigned an 1C circuit 
designation in the MC series. The Chief of 
Naval Operations authorizes these MC circuits 
for each class of vessel, based on size, com- 
plement, function, and operational employment. 
Authorized 1C announcing circuits are listed 



in Table 11-1, according to importance and 
readiness. These systems, however, are not all 
installed in any one ship. 



CENTRAL AMPLIFIER 
ANNOUNCING SYSTEMS 

Central amplifier announcing systems are 
designed to furnish amplified voice communica- 
tion and, in some cases, alarm signals to the 
various loudspeakers located throughout the ship. 
These systems transmit the spoken word or 
signal from a station, amplify the signal at a 
central amplifier, and radiate the signal from 
the loudspeaker or loudspeakers located in re- 
mote areas. 

As you can see in table 11-1, several of the 
MC systems are of the central amplifier type. 
The size of these systems ranges from the IMC 
system on an aircraft carrier to the very small 
by comparison, 29MC system on an old class 
destroyer. In many instances, the control and 
amplification facilities of several different MC 
systems may be combined. As an example: 
if a ship has a 6MC- system installed, it is 
usually combined with the IMC system. 



1MC-6MC Announcing 
Systems Equipment 

The combined 1MC-6MC systems installation 
provides general shipboard announcing (circuit 
IMC) and intership announcing (circuit 6MC) 
facilities. Additionally, a means of broadcasting 
various ship's alarms is provided in conjunction 
with, and as part of, circuit IMC. The typical 
1MC-6MC installation consists of: alarm contact 
makers, microphone control stations, loud- 
speakers, visual alarm indicators and the control/ 
amplifier equipment. Figure 11-1 is a block 



227 



SHIPBOARD ELECTRICAL SYSTEMS 



Table 11-1. Shipboard Announcing Systems 



Circuit 


System 


Importance 


Readiness Class 


*IMC 


General 


V 


1 


*2MC 


Propulsion plant 


V 


1 


*3MC 


Aviators' 


V 


1 


4MC 


Damage Control 


V 


1 


*5MC 


Flight Deck 


sv 


2 


*6MC 


Inter ship 


sv 


1 


7MC 


Submarine Control 


V 


1 


BMC 


Troop administration and control 


sv 


2 


*9MC 


Underwater troop communication 


sv 


2 


*10MC 


Dock Control (obsolete) 


sv 


1 


*11-16MC 


Turret (obsolescent) 


sv 


3 


*17MC 


Double Purpose Battery 








(obsolescent) 


sv 


3 


18MC 


Bridge 


NV 


2 


19MC 


Aviation Control 


sv 


2 


*20MC 


Combat Information 








(obsolescent) 


sv 


1 


21MC 


Captain 1 s Command 


sv 


1 


22 MC 


Electronic Control 


NV 


I 


23MC 


Electrical control 


sv 


I 


24MC 


Flag Command 


sv 


1 


25MC 


Ward Room (obsolescent) 


NV 


4 


26MC 


Machinery Control 


SV 


1 


27MC 


Sonar and Radar Control 


sv 


1 


*28MC 


Squadron (obsolescent) 


NV 


4 


*29MC 


Sonar Control and Information 


SV 


2 


30MC 


Special Weapons 


sv 


2 


31MC 


Escape trunk 


sv 


2 


32MC 


Weapons control 


sv 


3 


33MC 


Gunnery Control (obsolescent) 


sv 


3 


34MC 


Lifeboat (obsolescent) 


sv 


1 


35MC 


Launcher Captains' 


sv 


1 


36MC 


Cable Control (obsolete) 


NV 


4 


37MC 


Special Navigation (osbolete) 


sv 


2 


38MC 


Electrical (obsolete) 


NV 


1 


39MC 


Cargo Handling 


NV 


4 


40MC 


Flag Administrative 


NV 


1 


4 IMC 


Missile Control and Announce 








(obsolete) 


SV 


3 


42MC 


CIC Coordinating 


SV 


2 


43MC 


Unassigned 






44MC 


Instrumentation Space 


NV 


1 


45MC 


Research operations 


NV 


1 


*46MC 


Aviation Ordnance and Missile 








Handling 


SV 


2 


47MC 


Torpedo Control 


SV 


2 


48 MC 


Stores conveyor (obsolescent) 


NV 


1 


49MC 


Unassigned 






50MC 


Integrated operational 








intelligence center 


SV 


2 



27.123.0 



228 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



Table 11-1. Shipboard Announcing Systems continued 



Circuit 


System 


Importance 


Readiness Class 


51MC 


Aircraft Maintenance and 








handling control 


SV 


2 


52MC 


Unassigned 






53MC 


Ship Administrative 


NV 


4 


54MC 


Repair Officer's Control 


NV 


4 


55MC 


Sonar Service 


NV 


4 


56MC 


Unassigned 






57MC 


Unassigned 






58MC 


Hanger Deck Damage Control 


V 


1 


59MC 


SAMID Alert 


SV 


3 



Legend: 

* = Central amplifier systems 

V = Vital 
SV = Semivital 
NV = Nonvital 



27.123.0 



r 1 



ALARM 
CONTACT 
MAKERS 



CONTROL AMPLIFIER 

EQUIPMENT" I 






CIRCUIT IMC 

MICROPHONE 

CONTROL 

STATIONS 



CIRCUIT IMC S 
LOUDSPEAKER 



CIRCUIT IMC 86MCI 
i MICROPHONE 
I CONTROL 

| STATION i 

I 1 




' GROUPS 



CIRCUIT 6MC 1 
LOUDSPEAKER 

GROUP I 

(BULL HORN) j 



. VISUAL ALARM ' 
I INDICATORS \ 

J 



POWER FROM 

MAIN 1C 

SWBD 



>MUTING AND PRIORITY 

SIGNALS TO 

SHIP'S ENTERTAINMENT 
AND OTHER ANNOUNCING 
EQUIPMENT 



Figure 11-1. Typical 1MC-6MC systems installation. 

229 



140.125 



SHIPBOARD ELECTRICAL SYSTEMS 




7.19 

Figure 11-2. IMC - 6MC microphone control 
station. 



diagram of a typical 1MC-6MC systems instal- 
lation found aboard a destroyer. Power for oper- 
ating the system is obtained from the 120-V 
60-Hz distribution section of the main 1C switch- 
board. 

ALARMS AND ALARM CONTACT MAKERS. ~~ 
A number of different alarms may be generated 
within and broadcast over circuit IMC. The 
nature and number of alarms is dependent to 
some extent on the mission of the ship aboard 
which the system is installed. As a rule, how- 
ever, all IMC systems installed aboard surface 
ships are capable of generating and broadcasting 
collision alarms, chemical attack alarms, and 
general alarms. The alarms are generated by 
oscillators located within the control/ amplifier 
equipment. Alarms are activated by closing a 
lever-operated switch type contact maker (de- 
scribed in chapters). Each alarm that is generated 
and broadcast by the system has at least one 
of its own contact makers, i.e., the general 
alarm is actuated by a general alarm contact 
maker, the collision alarm is actuated by a 
collision alarm contact maker, etc. The alarm 
contact makers are installed at various locations 



such as the bridge and quarterdecks where they 
are easily accessible to watchstanders. 

The alarms are broadcast over circuit IMC 
only and they have priority over IMC voice 
transmissions. Additionally, a system of prior- 
ities is part of the alarms. The order of alarm 
priorities is (1) collision alarm, (2) chemical 
attack alarm and (3) general alarm, If a low 
priority alarm is being sounded and the contact 
maker for a higher priority alarm is closed, 
the lower priority alarm will be silenced and the 
higher priority alarm will be transmitted over 
the IMC loudspeakers. Conversely, the closure 
of a low priority alarm contact maker has no 
effect on a high priority alarm that is being 
sounded. 

MICROPHONE CONTROL STATIONS. 
Microphone control stations (fig. 11-2) provide the 
facilities to make voice announcements over the 
IMC or 6MC system and to select the loud- 
speakers over which the voice announcements 
will be broadcast. The microphone control station 
consists of a microphone with a press-to-talk 
switch, loudspeaker group selector switches, 
busy lamps, and a signal level meter. 

To make a voice transmission from a micro- 
phone control station, first, depress the loud- 
speaker group selector switches (crew, officer, 
engineers, etc.) over which you desire to make 
the transmission. Next, depress the press-to- 
talk switch and speak into the microphone with 
sufficient force to cause the deflections of the 
signal level meter pointer to peak at midscale. 
The busy lamps indicate that a transmission 
is in progress from another microphone control 
station. 

Ships usually have at least two microphone 
control stations. The bridge is equipped with a 
1MC-6MC microphone control station and the 
quarterdeck is equipped with a IMC only micro- 
phone control station, which does not have an 
intership loudspeaker (6MC) selector switch. 
The microphone control stations are also under 
a system of priorities as are the alarms. Bridge 
IMC transmissions have priority over the quar- 
terdeck IMC transmissions. Under certain con- 
ditions, which will be discussed later in this 
chapter, the IMC has priority over the 6MC. 

LOUDSPEAKERS AND LOUDSPEAKER 
GROUPS. Loudspeakers convert the amplified 
voice and alarm electrical signals to sound. 
Several different types of loudspeakers are used 
in 1MC-6MC systems to suit different needs. 
Figure 11-3 illustrates two loudspeaker types. 



230 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



HOUSING 




HORNS 



ROTATABLE 
BASE 



DOUBLE-FOLD HORN 
LOUDSPEAKER 



MULTIUNIT STRAIGHT-HORN 
LOUDSPEAKER 



Figure 11-3. Dynamic horn loudspeakers. 



7.17 



The double-fold horn is used with circuit IMC 
in weather decks or in high noise areas. The 
nultiunit straight-horn (bullhorn) is a high-power 
init used for intership (6MC) voice commani- 
lations. 

For purposes of selectivity and damage iso- 
ation, the various IMC loudspeakers are organ- 
zed into groups and subgroups. A typical 
lestroyer installation consists of four loud- 
speaker groups (1) officers, (2) topside, (3) 
jrew, and (4) engineers. A IMC voice trans- 
nission may be made via any one or all of the 
speakers by selecting the appropriate speaker 
froup or groups at the microphone control station. 
Jince the loudspeakers of the groups are separated 
nto physical zones, i.e., officers' country, engi- 
leering spaces, etc., a damaged loudspeaker in 
i group could result in the complete loss of IMC 
ransmission to an entire area of the ship. 
To overcome this handicap, groups are divided 
nto subgroups with an action cutout switching 
irrangemsnt. The subgroups consist of several 
oudspeakers from the parent group. Loud- 
jpeakers of the subgroup are selected so that 
lot all of the speakers of a space or geographical 
Lrea belong to a specific subgroup. A damaged 
oudspeaker of a IMC system subgroup may be 



isolated through the action cutout switching ar- 
rangement without completely losing IMC capa- 
bility to a major space or area. 

Usually one or two 6MC loudspeaker units are 
installed. The 6MC loudspeakers are not divided 
into groups. The desired 6MC loudspeaker is 
selected at the bridge microphone control station. 

VISUAL ALARM INDICATORS. Visual alarm 
indicators consist of lighting fixtures with red 
lamps installed in machinery spaces where high 
noise levels are common. The red lamp lights 
steady when the collision and chemical attack 
alarms are sounded and flashes when the general 
alarm is sounded. 

CONTROL/AMPLIFIER EQUIPMENT. The 
control amplifier equipment is the heart of the 
1MC/6MC system. All signals and control func- 
tions that are required for system operation are 
either processed by or developed within it. 
Control/amplifier equipment: 

1. Generates alarm signals of various charac- 
teristics when activated by the closure of an 
alarm contact maker. 



231 



SHIPBOARD ELECTRICAL SYSTEMS 



2. Amplifies voice and alarm signals to a 
magnitude sufficient to drive the many loud- 
speakers of the system, 

3. Channels the amplified voice signals to 
the specific loudspeaker groups as selected at 
the microphone control station. 

4. Channels the ordered alarm signals to all 
the loudspeaker groups of the system., 

5. Provides a backup amplifier and oscillator. 




AMPLIFIER-OSCILLATOR 
ASSEMBLY 



6. Provides facilities to control the volume of 
voice signals and to monitor, test, and isolate 
certain components of the system. 

7. Performs specific functions in accordance 
with a fruilt-in set of priorities. 

8. Energizes the visual alarm indicators when 
an alarm is sounded. 

The two units of the control/ amplifier equip- 
ment such as the one illustrated in figure 11-4 
contain the oscillators, preamplifiers, power 




POWER AMPLIFIER ASSEMBLY 

Figure 11-4. AN/SIA-114 control/amplifier equipment. 

232 



140.36 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



Table 11-2. Alarm Signal Characteristics 



Signal 



Characteristic 



Collision Alarm 
Chemical Alarm 
General Alarm 
Unassigned Alarm "A" 
Unassigned Alarm "B" 
Flight Crash Alarm 



Triple pulsed 1000 Hertz tone 

Continuous 1000 Hertz tone 

Gong tone 

500-1500 Hertz jump tone (1 1/2 per sec) 

600-1500 Hertz jump tone (6 per sec) 

Simulated siren tone 



amplifiers, and control devices necessary for 
the system to perform as stated above. 

Oscillators. The oscillators provide the 
various alarm signals required for the system. 
The sound characteristics of each alarm are 
different so that each may be easily distinguished 
from the others. The sound characteristics for 
each alarm have been standardized (table 11-2) 
on surface craft so that the alarm signals on 
all ships are identical. Only three alarms 
collision, chemical attack, and general have 
been mentioned thus far. These three alarm 
signals may Tbe sufficient for some ships, whereas 
for other ships additional alarm signals may be 
required. So that the control/amplifier equipment 
may be installed on several classes of ships, 
the oscillators of most equipment are capable 
of producing other designated alarm signals, such 
as the flight crash alarm. They are also capable 
of producing signals that are not designated by 
name, but are reserved for future use. The 
oscillators of the equipment shown in figure 11-4 
produce two such alarm signals the unas signed 
alarm "A" and the unassigned alarm "B." 
These two alarm signals have their own individual 
sound characteristics and are reserved for future 
use as may be directed by higher authority. 

The control/amplifier equipment has two 
oscillator subassemblies which are contained 
within the amplifier-oscillator assembly. Only 
one of the two oscillators is required to produce 
the alarm signals required of the system. A 
rotary selector switch located on the front panel 
)f the amplifier-oscillator assembly is used to 
select which oscillator will produce the system 
alarm signals a The inactive oscillator is then 



available for maintenance- or repair, or to produce 
signals that may be used to test an inactive pre- 
amplifier and power amplifier. 

Preamplifier and Power Amplifier. The 
preamplifier is contained within the amplifier 
oscillator assembly. It amplifies the weak voice 
signals from the microphones and the alarm 
signals from the oscillators to a value sufficient 
to drive the power amplifier. To compensate for 
the different voice levels of system users, the 
preamplifier contains special circuits which at- 
tenuate those high level input signals that would 
cause overdriving and distortion at the loud- 
speakers. 

The power amplifier is contained in the 
power amplifier assembly and receives the 
relatively weak voice signals and alarm sig- 
nals from the preamplifiers and greatly in- 
creases their power level to a level that is 
sufficient to drive the loudspeakers. The sig- 
nals from the power amplifier are returned to 
the amplifier-oscillator assembly for distribution 
to the different speaker groups. 

One preamplifier in conjunction with one 
power amplifier form one channel. Usually, 
there are two preamplifiers and two power 
amplifiers in the 1MC-6MC system connected 
to form two channels (channel A and channel 
B), The equipment shown in figure 11-4 contains 
two amplifier channels each of which is capable 
of producing 500 watts of audio power. 

The two identical amplifier channels are 
provided to permit independent operation of 
the IMC and 6MC systems if desired, one system 
on each of the two channels. A channel selector 
switch is provided on the front panel of the 



233 



SHIPBOARD ELECTRICAL SYSTEMS 



amplifier-oscillator assembly to provide flexi- 
bility to the system. The selector switch can 
be positioned for systems operation as follows: 

1. IMC on channel A, 6MC on channel B 

2. IMC and BMC on channel A 

3. IMC and 6MC on channel B 

The last two combinations may be used to 
isolate one of the channels for service. The 
first position listed is used for independent 
operation of the IMC and 6MC. 

Because a large amount of heat is radiated 
from the power amplifiers, many ships operate 
with both systems on the same channel, with the 
remaining channel secured and in reserve. This 
mode of operation greatly reduces the radiated 
heat and resulting insulation deterioration. As 
the 6MC system is used seldom, as compared 
to the IMC system, operating in this manner 
presents few operational disadvantages. However, 
it does extend equipment life. 

As previously discussed, under certain cir- 
cumstances the IMC voice transmissions have 
priority over 6MC voice transmissions. When the 
system is operating with the IMC on amplifier 
channel A and the 6MC on amplifier channel 
B, it is possible to broadcast over the 6MC 
system from the bridge microphone station and, 
at the same time, to broadcast over the IMC 
from the quarterdeck microphone station. When 
both systems are operated on the same amplifier 
channel, IMC transmission takes priority over 
6MC transmissions. 



1MC-6MC Announcing 
Systems Operation 

The 1MC-6MC system, as stated previously, 
provides a means of transmitting IMC alarms, 
IMC voice, and 6MC voice. Listed below are basic 
descriptions of how the systems perform these 
tasks. The descriptions are general in nature and 
vary depending on the particular equipment and 
installation. 

IMC ALARM TRANSMISSIONS. Transmis- 
sion of a IMC alarm begins when an alarm 
contact maker collision, chemical attack, or 
general is closed. Closure of the contact maker 
energizes a specific relay for that alarm, setting 
in motion a sequence of events within the control/ 
amplifier equipment which disables the circuitry 



for other alarms having lower priority and com- 
pletes the circuits that cause a nurnber of other 
relays to operate to: 

1. Energize the on-service oscillator in such 
a manner as to cause it to produce the desired 

sound. 

2. Establish priority over 1MC-6MC voice 

transmissions. 

3. Illuminate the busy 1 and busy 2 (IMC 
busy and 6MC busy) lamps at the microphone 
control stations to alert personnel that IMC 
and 6MC voice transmissions are not possible. 

4. Provide a control signal to ship's enter- 
tainment and other announcing equipment to 
mute or disable it. 

5. Connect the output of the selected oscillator 
to the input of the amplifier channel selected 
for IMC transmissions. 

6. Apply power to the selected amplifier 
channel. 

7. Operate all the loudspeaker group relays 
so that the alarm signal will be transmitted over 
all of them. 

8. Energize the visual alarm indicators - 
steady for collision and chemical attack alarm, 
intermittent for general alarm. 

For the collision and chemical attack alarms, 
the above conditions will continue to exist only 
as long as the contact maker is closed. Momentary 
operation of the general alarm contact maker 
causes the alarm to sound for a predetermined 
15-second period. 

IMC VOICE TRANSMISSIONS. Operation of 
the microphone press-to-talk switch at the micro- 
phone control station sets up the following se- 
quence within the control/ amplifier equipment, 

1. Connects the microphone output to the 
input of the amplifier channel selected for IMC 
transmissions. 

2. Causes the loudspeaker group relays to 
energize for those loudspeaker groups that have 
been selected at the microphone control station, 
This action connects the output of the amplifier 
channel to those loudspeaker groups over which 
it is desired to transmit the voice information, 

3. Energizes the busy lamps on the micro- 
phone control stations as follows: 

a. IMC on channel A and 6MC on channel 
B: the busy 1 (IMC busy) lamp is illuminated 
at all microphone control stations. 

b. 1 MC and 6MC on channel A or IMC 
and 6MC on channel B: both the busy 1 and busy 



234 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



2 (IMC and 6MC busy lamps) are illuminated 
at all microphone control stations. 

4. Establishes IMC priority over the 6MC 
transmission if both the IMC and SMC systems are 
sharing the same amplifier channel. 

5. Sends control signal to the ship's enter- 
tainment to mute its transmission. 

6. Applies power to the amplifier channel 
selected for IMC service. 

7. The operator makes his transmission 
through the microphone, regulating the force 
of his voice, to cause the pointer of the meter 
on the microphone control station to peak at 
mtdscale deflection. 

6MC VOICE TRANSMISSIONS. 6MC voice 
transmissions are very similar to IMC voice 
transmissions. 6MC transmissions differ mainly 
in that: 

1. They can only be made from the bridge 
>r other specifically designated 1MC-6MC 
nicrophone control stations. 

2. The 6MC loudspeaker is selected as op- 
>osed to the IMC loudspeaker groups. 

3. The busy lamps on the microphone control 
stations are energized as follows: 

a. IMC on channel A and 6MC on channel 
3: the busy 2 (6MC busy) lamp is illuminated 
.t all microphone control stations. 

b. IMC and 6MC on channel A or IMC 
.nd 6MC on channel B: both busy lamps are 
Lluminated at all microphone control stations. 

laintenance and Safety 

Maintenance personnel must be very careful 
r hen servicing this equipment. All the common 
ales of safety and good sense apply, as they 
r ould to any other electrical equipment. Special 
are should be exercised with this equipment, 
owever, because: 

1. Voltages in excess of 1,000 volts maybe 
resent within the control/amplifier equipment. 

2. The sound pressure level emitted from a 
MEG loudspeaker (bullhorn) is very high. Trans- 
tission should not be made over the 6MC 
/stem while personnel are in the vicinity of the 
mdspeaker. 

JTERCOMMUNICATING 
iTSTEMS 

An intercommunicating (intercom) system 
msists of a number of permanently located 



stations. Each station contains all the necessary 
components to provide two-way amplified voice 
communication, supplemented by signal lamps, 
between two stations. The units used in intercom 
systems serve the same purposes and operate 
basically the same as the commercial intercom 
units so common in many business offices. 
Navy and commercial intercom units differ mainly 
in their physical appearance. The typical intercom 
systems used aboard naval ships consist of a 
number of compatible intercom units and their 
interconnecting cabling. 

Intercom Unit 

There are several basic types of intercom 
units in use throughout the Navy, with certain 
variations to the basic types. These types differ 
mainly in physical appearance and in the materials 
used in their construction. Irrespective of their 
appearance and construction, their electrical 
characteristics have been standardized to permit 
intercom units of different manufacturers and 
construction to be used in one common system,, 

Figure 11-5 illustrates two intercom units. 
The units are made by different manufacturers 
but they are compatible, and each is capable 
of originating calls to as many as 10 other 
intercom units. There are similar units which 
can call 20 other stations, and there is another 
type which can originate calls to only two other 
stations. 



SHIP'S ENTERTAINMENT 
SYSTEMS 

A separate shipboard announcing system, 
circuit SE, is used primarily for the entertain- 
ment of ship's company and is capable of broad- 
casting commercial radio programs, prerecorded 
information, and voice announcements of an 
educational or entertainment nature to various 
locations within the ship. 



SHIP'S ENTERTAINMENT 
EQUIPMENT 

There are several different types of ship's 
entertainment equipment which is specifically 
manufactured for installation aboard naval ships. 
In addition, many ships have ship's entertainment 
systems which are composed in part or entirely 
of equipment designed for commercial use. 



235 



SHIPBOARD ELECTRICAL SYSTEMS 





7.25:140.127 
Figure 11-5. Intercom units. 



Figure 11-6 is a diagram of a typical ship's 
entertainment system. This system consists of 
various input equipment, a control/ amplifier 
console, power amplifier assembly, and as many 
loudspeakers as required. 

Input Equipment 

The input equipment consists of those devices 
that supply the desired entertainment or educa- 
tional programs to the ship's entertainment sys- 
tem. The actual composition of input equipment 
may vary, depending on the particular installation. 
A typical selection of input equipment is illus- 
trated in figure 11-6. An additional phonograph, 
tape player, radio, etc. may be connected to the 
auxiliary input jack if desired. 

Control/ Amplifier Console 

The control/ amplifier console pictured in 
figure 11-6 is used in many shipboard installa- 
tions. The console together with the power 
amplifier assembly contains the necessary con- 
trol devices and amplifiers to accept from 
any two of the available inputs and to retransmit 
that information over two independent channels 
to the various loudspeakers. The console also 
contains a tape recorder that may be used as an 
input for one of the entertainment channels, 
or it may be used to record information for 
later use. As previously discussed in this chapter, 
control signals from the 1MC-6MC system actuate 
devices within the console which mute or silence 
ship's entertainment transmissions. 

Loudspeakers 

Ship's entertainment speakers are installed in 
berthing, messing, and recreation spaces. Each 
speaker unit is provided with a channel selector 
switch and volume control to permit the individual 
to select and regulate the volume of the channel 
he desires to hear. The loudspeakers of the 
ship's entertainment system are arranged in 
groups as they were in the 1MC-6MC system* 
Isolation switches (located on the control/ 
amplifier console) permit individual speaker 
groups to be disconnected from the remainder 
of the system if desired. 

Commercial Ship's 
Entertainment Equipment 

The entertainment systems aboard many ships 
are composed in part or entirely of commercial 



236 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



INPUT 

EQUIPMENT 



CONTROL/AMPLIFIER 
CONSOLE 



LOUDSPEAKERS 










SELECTED 
CHANNEL 182 

INFORMATION FROM CONTROL/ 

AMPLIFIER CONSOLE TO 

POWER AMPLIFIER ASSEMBLY 



CHANNELS 182 



CHANNELS 1S2 




CHANNELS 18 2 



CHANNELS 182 




CHANNEL 1 8 2 

t INFORMATION FROM POWER 
AMPLIFIER ASSEMBLY TO 
CONTROL AMPLIFIER 
CONSOLE FOR DISTRIBUTION 
TO LOUDSPEAKERS 



POWER AMPLIFIER ASSEMBLY 



27.340 



Figure 11-6. -Basic diagram of ship's entertainment equipment. 

237 



SHIPBOARD ELECTRICAL SYSTEMS 



equipment* This commercial equipment usually 
is more compact, less expensive, and more 
attractive than Navy equipment, but it presents 
certain disadvantages that should be considered 
prior to its purchase and installation. Some 
disadvantages are; 

1, Safety commercial equipment is not al- 
ways electrically safe for shipboard use. 

2, Construction- commercial equipment is 
not always rugged enough to withstand the rigors 
of shipboard use. 

3, Supply support commercial equipment is 
not supported by the Navy Supply System* In 
many instances it will be very difficult to obtain 
repair parts for commercial equipment* 

SHIP'S ENTERTAINMENT 
SYSTEM OPERATION 

A properly maintained and operated ship's 
entertainment system contributes greatly toward 
a happier ship's company, A poorly maintained 
and incorrectly operated ship's entertainment 
system is worse than having no system at all. 
It should be remembered that, at many times, 
the entertainment system is often the only source 
of world news and one of the few sources of 
entertainment for the ship's company. It should 
also be remembered that no two person's opinion 
of what constitutes entertainment agrees com- 
pletely, and it is impossible to please everyone 
all the time. 

The entertainment system should present a 
wide variety of programs. If possible, pro- 
gramming should be done by several persons 
of varied interests. Many times it will be possible 
to enlist the services of crew members in 
scheduling programs for the system. 



SOUND MOTION PICTURE 
SYSTEMS 

Sound motion picture systems are designed 
for training, briefing, and entertaining. The 
equipment used is similar to commercial motion 
picture projection equipment which projects 
16-mm sound film for viewing. The types of 
equipment used and the size of installation vary 
with each ship. Usually ships are equipped with 
at least two 16-mm sound motion picture pro- 
jectors and several installed or portable loud- 
speakers. 



SOUND MOTION 
PICTURE FILM 

The sound motion picture film Is one of the 
most expensive components of a sound motion 
picture projection system? it is also the most 
susceptible to damage. 

Film Construction 

Sound motion picture film used by the Navy 
is identical to that used by the civilian population. 
It is composed of a nonflammable cellulose 
acetate base upon which is bonded the emulsion. 
The base supports and acts as the transporter 
or vehicle for the emulsion. The emulsion is 
the component in which the image, including 
the sound track, is recorded by the photographic 
process. Figure 11-7 is an exploded view of 
motion picture film. The edge of the film is 
perforated by sprocket holes, which are used 
to aid in transporting the film through the movie 
projector mechanisms. The opposite edge of the 
film contains the photographic record of the 
sound recording, the sound track. As shown 
in figure 11-7 the image appears inverted to the 
observer. The projection process causes the 
image to once again appear right side up on the 
movie screen. 

Film Care 

The care of motion picture films is largely 
a matter of common sense. Navy motion picture 
films should receive the same care as one 
would expect to give his own films. Store them 
in a cool, dry place and handle them carefully. 

Most film damage is a result of improper 
care, defective projection equipment, or improper 
stowage. The most common types of film damage 
are liquid damage, scratches, and tearing. 

DAMAGE FROM LIQUIDS, Most liquids (in- 
cluding water) will damage the emulsion surface 
of films. Exposure to liquids causes the emulsion 
to become discolored; figures and colors run 
together. The most common cause of this form 
of film damage are improper stowage and the 
careless coffee drinker. 

SCRATCHES. The emulsion of the film is 
a relatively soft material, and it is easily 
scratched. Scratched films appear to have vertical 
lines or bars across them and the reproduced 
sound portion of the film is distorted. Improper 
handling, defective projection equipment and poor 



238 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



SOUND TRACK 



PICTURE FRAME 
SPROCKET HOLE [UD 



PICTURE UPSIDE 
DOWN 




7,66(77C) 
Figure 11-7. Section of 16-mm film, 



projector operators cause most scratched film 
damage. To avoid this form of damages 

1. Exercise care to keep the film and pro- 
jection equipment as clean as possible. 

2. Keep the projection equipment properly 
adjusted. 

3. Ensure that projection equipment operators 
are properly trained. 

TORN OR BROKEN FILM e Gross mishand- 
ling by projection equipment operators or de- 
fective equipment results in broken or torn 
film. This type of damage can be prevented by 
properly maintaining your projection equipment 
and properly training its operators. 

Film Management 

Generally, motion picture film available to 
shipboard personnel may be categorized as being 
either educational or entertaining in nature. 



The policies for use, management, and distri- 
bution of each type is different. Entertainment 
films are under the cognizance of the Navy 
Motion Picture Service, while the policies con- 
cerning educational films are established by 
the Chief of Naval Education and Training. To 
ensure the efficient utilization of each type of 
film, several reports and forms must be main- 
tained by shipboard personnel. The records 
required for educational films are different 
from those required for entertainment film. 

ENTERTAINMENT F I L M. Entertainment 
film for shipboard viewing is available through 
your local Navy Motion Picture Exchange (MPX). 
The rules governing the operation of local MPX's 
and the use of their films by shipboard personnel 
are contained in the Navy Motion Picture Service 
Manual. This manual covers all aspects of enter- 
tainment film usage and handling and gives 
information on the use of forms, reports and 
records that are part of the system. The manual 
also specifies that all movie projector operators 
are to be adequately trained and designated in 
writing by the commanding officer. Failure to 
comply with the regulations contained within 
the manual could result in the suspension of 
your command's entertainment film privileges. 

For purposes of familiarization, some of 
the records and forms associated with enter- 
tainment films are listed below. You should 
consult the Navy Motion Picture Service Manual 
for specific instructions concerning these records 
and forms. 

Inspection and Exhibition Booklet. Each en- 
tertainment film print has its own Inspection 
and Exhibition Booklet (I & E Booklet) which 
remains with the film as long as it is in service. 
The I & E Booklet serves several functions. 
The first pages contain a brief description of 
what the film is about and lists the major stars 
that appear in it. The remaining pages (fig. 11-8) 
are a record of where and when the film has 
been exhibited and its condition before and after 
each exhibition. This information aids the MPX 
in determining who may be responsible for any 
damage to the film and it also helps in determining 
that a film has been used sufficiently to warrant 
its removal from circulation. Entries on the 
record pages shoyild be brief, legible, and specific. 
They should be made in ink, and each entry mast 
be signed by the designated movie officer. These 
entries are checked by MPX personnel when 
the film Js returned. 



239 



SHIPBOARD ELECTRICAL SYSTEMS 



SHIP OR STATION 



DATE OF 
EXHIBITION 



CONDITION BEFORE 
EXHIBITION 



CONDITION AFTER 
EXHIBITION 



SIGNATURE 
COMMISSIONED OFFICER 



S.S. 



G-oocL 



G 



U.S. 



8-3-73- 



GOoD C.Q M$ i T"/ o /J 



GoocL 



g,9.s 



3-1-73 



Good 



Figure 11-8. Inspection and Exhibition Booklet Record pages. 



27.394 



PROGRAM NO. 



MOTION PICTURE PRINT INVENTORY CARD 

NAVPERS 3045 (REV 1971) 

INSTRUCTIONS: (REPORT SYMBOL BuPers 1710-6) 

TO THE SHIP OR STATION HAVING CUSTODY OF THIS PRINT 

1. DETACH THIS CARD ON THE LAST DAY OF THE ABOVE MONTH. 



PRINT NO. 



MONTH 




YEAR 



2. ENTER U-I-C CODE AND ADDRESS IN THE SPACES PROVIDED BELOW. 

3. IF THIS PRINT IS RECEIVED WITH A CARD(S) FOR A PREVIOUS 
MONTH(S), DETACH AND SUBMIT CARD(S) IMMEDIATELY. 



4. THIS. IS A MONTHLY PRINT INVENTORY CARD 
AIRMAIL TO: 

NAVY SPECIAL SERVICES ADMINISTRATIVE ACTIVITY 
NAVY MOTION PICTURE SERVICE 
311 FLUSHING AVENUE 
BROOKLYN, NEW YORK 11205 



PROGRAM! PRINT 



14 1'5 16 17 18 19 



DO NOT BEND OR FOLD 



SENDERS CORRECT MAILING ADDRESS INCLUD NS ZIP CODE 













U I. C. 



27.395 



Figure 11-9. -Motion Picture Inventory Card. 



Motion Picture Print Inventory cards (fig. 
11-9) are attached inside the rear cover of the 
I & E Booklet and provide information for the 
Navy Motion Picture Service to periodically 
account for each film and its general location. 
Use of the cards is self-explanatory. 



Motion Picture Inspection Record. Motion 
picture exchanges generally require shipboard 
personnel to complete a record of inspection 
prior to the receipt of a print. Figure 11-10 
is a checkoff list which serves as a guide to 
the representative from your command and aids 



240 



Chapter 11 AMPLIFIED VOICE SYSTEMS 













INSTRUCTIONS 
a. For preparation by movie operator prior to exhibiting of each 

MOTION PICTURE INSPECTION RECORD jw*-* **//*.,* 
NAVPERS 3043 (Rev. 4-61) *' *" "" by NMPX ' S in making ro ""' ae ia *"' ions ' 


PROGRAM NUMBER 


PROGRAM CONDITION CODE 




GENERAL PRINT 
CONDITION 


SPECIFIC DEFECTS NOTED 


E EXCELLENT 
G GOOD 
U USABLE 
NU NON-USABLE 


B BRITTLE HS HEAVY SCRATCH SPL LIGHT SPROCKET DAMAGE 
C CRIMPS M MISSING SPH HEAVY SPROCKET DAMAGE 
LS LIGHT SCRATCH N NICKS W WATERMARKS 


FEATURE f-f -~ 


OC/<^ AMOA/Y/Mnts^ 


NO. REELS 

3 


SHORT SUBJECTS 


#2 


#3 


TOTAL REELS Jg 


INSPECTION FACTORS SHORT SUBJEaS 


REELS OF FEATURE 


(Vie above code) # } 


#2 #3 12 


3 


4 S & 


PROTECTIVE LEADER 


G, M 


G 




SYNCHRONIZING LEADER 


G M 


G 




TITLE AND CAST 


L5 G 


3 




PICTURE 


Gi uy 


G 




SOUND TRACK 


L5 G 


G 




ALONGSIDE SOUND TRACK 


Cji C^ 


q 




SPROCKET HOLES 


{* p) / ^ 


Q 




SPLICES 


C G 


G 




ENDING 


G 


/Wi 




GENERAL PRINT CONDITION 


(Use Code abort) ^ 




REMARKS 




DISPOSITION 

NMr- 


>X USE 


VAULT 

A/MF*K a<&- 


DATE 

/7 3 


'ULY 76 


SIGNATURE (Inspector) 


SIGNATURE OF MOTION PICTURE OFFICER PRIOR TO EXHIBITION 





Figure 11-10. Motion Picture Inspection Record. 

241 



77.269 



SHIPBOARD ELECTRICAL SYSTEMS 



him in his inspection. Performing an inspection 
at the Motion Picture Exchange and noting the 
condition of the film will prevent your ship's 
being held responsible for previous damage. 

Activity, Damage, Loss and Destruction 
Report. Upon the discovery of loss, damage, 
or destruction of a print, the Motion Picture 
Exchange will initiate and forward an Activity, 
Damage, Loss and Destruction Report (fig. 11-11) 
to the command that last had custody of the 
damaged or lost print. The form is divided 
into two parts. The top half is filled out by the 
investigating MPX. The activity from which the 
information is requested completes the lower 
portion and returns the form to the requesting 
MPX. The MPX will attempt to affix the blame 
for the damaged print by the information received. 

Exhibition, Transfer and Inventory Record, 
The Exhibition, Transfer and Inventory Record 
is a monthly record of each film received by a 
ship. All films received by your command are 
recorded on this form. This form (fig. 11-12) 
lists the name of the print, from whom it was 
received, its condition after exhibition, and to 
whom it was transferred. The form also lists 
those personnel from your activity who were 
designated as projectionists. A new form must 
be prepared each month* It must be signed by the 
commanding officer or his designated repre- 
sentative (movie officer). The completed Motion 
Picture Exhibition, Transfer and Inventory 
Record forms should be retained aboard. 

Notification of Motion Picture Transfer. 
When ships are underway for extended periods 
or when they are in ports not serviced by an 
MPX, motion pictures may be transferred di- 
rectly from one ship to another. When such 
exchanges are made, the Notification of Motion 
Picture Transfer Form (fig. 11-13) must be 
completed. This form, when filled out and signed 
by a representative of the receiving command, 
is a receipt for films transferred from your 
command. 

Transfers are NOT to be made directly 
between ships in a port served by an MPX. 
Films are NOT to be informally loaned to other 
commands. Remember that your activity will 
be held responsible for any damage or loss that 
occurs to a film while it is officially in your 
custody. 

Request for 16-mm Motion Picture Sea 
Prints. Generally, film prints issued for use 



by ships while they are in port may NOT be 
taken to sea. Film prints that are to be taken 
to sea must be specifically requested on a 
Request for 16 mm Motion Picture Sea Prints 
Form (fig. 11-14). Instructions for completion 
and submission are listed on the form. 



TRAINING FILMS, In comparison to enter- 
tainment films the record keeping chores con- 
cerned with Navy training films are minor. 
Films which are of general interest to shipboard 
personnel are available from the Naval Education 
and Training Support facilities in San Diego 
and Norfolk. They may be obtained through 
official correspondence with these support facil- 
ities. Loss or damage to training films should 
be reported to the applicable support facility. 
A complete listing of available training films is 
contained in the United States Navy Film Catalog, 
NAVAIR 10-1-777. 



SOUND MOTION PICTURE 
PROJECTION EQUIPMENT 

The principles of operation of Navy pro- 
jection equipment are identical to those of com- 
mercially available equipment. The 16-mm Singer 
Graflex Movie Projector (fig. 11-15) is a slightly 
modified version of commercially available 
equipment. This projector, however, unlike its 
civilian counterparts, has been tested and is 
considered safe for shipboard use. The fact that 
it is considered safe for shipboard use does 
not mean that it will remain so indefinitely. 
It means that insofar as could be determined 
by the testing program, when used in a reasonable 
manner, the projector is as safe as it is tech- 
nically and economically feasible to make it. 

NOTE: MOVIE PROJECTORS, LIKE ALL 
PORTABLE ELECTRICAL EQUIPMENT 
ABOARD SHIP, ARE POTENTIAL SHOCK 
HAZARDS AND SHOULD BE TREATED AS SUCH* 



A movie projector's portability makes it 
susceptible to physical damage which could make 
it unsafe for use. Its portability means that it 
is not physically bonded to the ship's hull; 
physical damage could cause dangerous voltages 
to be present on its outer surfaces. These 
voltages await a person's contact which will 
cause current to flow through his body to the 
ship's hull. 



242 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



TRUCT.ON REPORT 



.. 6 April 197- 



From: Of f i cer-l n-charge , Navy Motion Picture Exchange. NORFOLK, VA. 



MPE - 100 



To: 



Commanding Officer 
U.S.S. UNDERWAY (AD- 12) 
c/o Fleet Post Office 
New York, N.Y. 



Subj : PROGRAM . 



2250 



A2 



FEATURE TITLE CROOKS ANONYMOUS (STD) B&W 



SHORT SUBJECTS PENNY PALS (STD) E 



1. Subject film was recently exhibited at your activity. It ia requested that information be furnished 
concerning: 

[j Damage of film Q] Loss of film 

2. After completing the items below forward this form an indicated. 

/s/ A.J. JONES, LT., USN 



(Signature) 



From- U S S UNDERWAY (AD-12) 



185 10 April 197- 

!IAL DATE 



(activity name) 

To: Officer-in-charge, Navy Motion Picture Service, Naval Station, 136 Flushing Ave., Brooklyn I, N.Y. 11251 



1. As requested above 


the following report 


is submitted: 










1 April 197- 




NUMBER OF SHOWINGS ON BOARD 

TWO 


Is operato 

E 


r an MPO school 
YES [""I NO 


graduate? 


[X] YES 


n NO 


during 


projection and after 

EYES 


showing? 

a NO 


prepared? 

E 


YES [I] 


NO 







Motion Picture Inspection Record (Navpers 3043) for program 2250 - A2 indicates that 
subject program was in GOOD condition before and after each of the two exhibitions on 
board. 



/s/ R.J. COX, LCDR, USN 



Figure 11- 11, Activity Damage, Loss and Destruction Report. 

243 



77.270 



SHIPBOARD ELECTRICAL SYSTEMS 



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26 
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EXH 

NAVP 



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CD 





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5S 

< CC 

Z 

31 



&. 



DA 
NSFE 
9 



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& 



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txO 

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5 

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Q H 
< 



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sS 



CNJ 



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CM 
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244 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



NOTIFICATION OF MOTION PICTURE TRANSFER 

HAMPERS 1710/1 (11-66) 

(Formerly HAVPE8S 3042) 



Navy Motion Picture Service, Naval Station, 136 Flushing Ave.. Brooklyn. N. Y. 11251 
Officer in Charge , Navy Motion Picture Exchange, Naval Station, Pearl Harbor, Hawaii 



CERTIFIED NO. TCMD NO. SIGNATURE 


INSURED NO. A NO, 


PROGRAM AND 
PRINT NUMBER 


NUMBER 
OF REELS 


PRODUCTION TITLE 






* TCK 0N001414112P013-XX 


2606-P15 


3 


THE WHISPERERS 


2607-P15 

2608-P15 
2609-P15 


3 
1 
3 
3 


OUR MAN FLINT 
SPOTLIGHT ON TASMINIA, TELE SPORTS #723 
ACT ONE 
THE MAN FROM NOWHERE 


NO ENTRY BELOW THIS LINE 






1 BDLE - 71 LBS. -1.6 CtJFT. 






PLEASE RECEIPT COPY & RETURN 


DATE RECEIVED SIGNATURE 

4/10/71 la/ 1. M. CASSADY, CDR, USN 



INSTRUCTIONS 



Forward original and a copy to the receiving activity via Air Mail. One copy shall accompany shipment and one copy shall be 
ailed to the Navy Motion Picture Service, U.S. Naval Station, 130 Flushing Avenue, Brooklyn, New York 11251. Originator shall 
ter all necessary shipping information in the spaces provided at the tup of this form. Listing for each film program shall include the 



g fo 
tle o 



m prog 

complete program number with print designator, number of reels in program and feature title of program. Each listing is understood 
to be one case unless otherwise indicated. Receiver shall acknowledge receipt by entering date of receipt and signature in the spaces 
p 
li 



. 

rovided at the boitom of this form and promptly return a copy to the originator. Receiver shall also clear!/ indicate any programs 
isted above but not received. 



77.268 



Figure 11-13. Notification of Motion Picture Transfer. 

245 



SHIPBOARD ELECTRICAL SYSTEMS 



REQUEST FOR 16 MM MOTION PICTUR 

FLTGEN Form 1710/1 (Rev. 12/66) 0199 217 1 

REF: COMSERVLANTINST 1700.4 ser 
1. All requests will be filled out in fill 


E SEA PRINTS 

013 


m F^. \ct76 


(Date) 

ies /OT Com Sefv Pac 

1. (Information classified CONFIDENTIAL, is to be included and the 


request classified CONFIDENTIAL. Information classified higher than CONFIDENTIAL is to be omitted and 
the statement "CLASSIFIED HIGHER THAN CONFIDENTIAL " inserted in the appropriate blanks.) 

2. Request for 14 sea prints or less are to be submitted directly to the Officer-in-Charge of the NMPX where 
prints will be drawn. 

3. Requests for 15 or more sea prints shall be submitted in original and two copies, to COMSERVLANT with a 
copy to the NMPX where prints are to be drawn. Requests should be submitted at least 14 days prior to the date 
required, whenever possible. 

4. Sea prints are to be drawn from the NMPX nearest the port of departure unless a draw from another NMPX is 
specifically authorized by COMSERVLANT. 

5. Atlantic NMPX's are located in ARGENTIA, BOSTON, BROOKLYN, CHARLESTON, GUANTANAMO, 
KEY WEST, LONDON, MAYPORT, NAPLES, NEW LONDON, NEWPORT, NORFOLK, PHILADELPHIA, 
RODMAN, SAN JUAN, and aboard deployed FBM Submarine Tenders (To be used primarly asSSBN exchanges). 


From: Commanding Officer, ^J^ ^ 


^ to / - 
^, rsfcfcl4STORH V t 


)) 


To: 


(Nome of Ship/Activit 


y) 


NO. PRINTS REQUESTED NO. PERSONNEL PORT OF DEPARTURE 

23 378 NORfoix, V/A 


ETD (TIME AND DATE* 

0^00 ^ MlW 1*176 


NO. SHIPS IN COMPANY ISSUING NMPX 

14MPX. NORfCtK, VA. 


PICK-UP DATE 

T HAP, l\T6 


NEXT PORT SERVICED BY NMPX 

BoOHAW, PfefsJAtM* 


ETA (TIME AND DATE) SI 


GNATURE ( (CO OR DESIGNATED AUTHORITY) 

A.V. STRAND IcR 
CAPt, U.S.M. 


COPY TO: 




FOR NMPX USE ONLY 




DATE NO. OF SEA PRINTS ISSUED AF 


PROVED BY: 

C^ Hu PftO 


REMARKS: 


1 



Figure 11-14. Request for 16-mm Motion Picture Sea Prints, 

246 



27.396 



Chapter 11 AMPLIFIED VOICE SYSTEMS 




Figure 11-15. 16-mm Singer 
projector. 



27.397 
Graflex movie 



Projector Maintenance, 
Uare, and Safety 

Improperly maintained movie projectors have 
)een the cause of several electrical shock fatali- 
les and many injuries. Ensure that only approved 
uid properly maintained motion picture equip- 
nent is used aboard your ship. Strictly adhere 
;o 3-M Maintenance requirements and proce- 
lures. 

A properly indoctrinated operator is, Tby far, 
he greatest asset in properly maintaining movie 
projectors and film* 

The routine projector cleaning performed by 
he operator, prior and subsequent to each film 
ihowing, is extremely vital to the longevity 
>f equipment and film. Dirt within the projector 
jollects on surfaces that come in contact with 
he film. This dirt, if allowed to accumulate, 
*esults in scratched film. Dirt also finds its 
yay into the projector's mechanisms and ac- 
selerates their deterioration. When badly worn 
irojector components cannot maintain alignment 
vith respect to each other, the resulting mls- 
ilignment causes improper projector operation 
.nd torn or broken film. 

Improper handling of the film and projector 
>y the operator is another cause of damage to 
oth film and projectors. A large amount of 



damage results from mishandled film and pro- 
jector or incorrectly operated projection equip- 
ment. 

The results of improperly trained projector 
operators have been listed above. However, the 
most important reason for training projector 
operators is for personal safety. 

A properly trained operator is more aware 
of what could be a hazard to him or others 
and of what actions he should take when he 
detects a hazard. 

Movie Projector 
Operator Training 

Only those personnel who have been properly 
trained and designated as qualified operators of 
projection equipment may operate movie pro- 
jectors aboard ship. Training and qualification 
are essential because of the potentials for elec- 
trical hazard and film damage associated with 
the equipment. A programmed instruction 
consisting of two volumes (16-mm Projector Op- 
erator, NAVEDTRA 5053-1&2, stock Nos. 0502- 
LP-025-2650 and 0502-LP-025-2660, Volumes 
1&2 respectively) is available for training movie 
projector operators aboard ship. Completion 
of the programmed instruction and on-the-job 
training should provide sufficient knowledge for 
the trainee to meet the qualification standards 
as set forth in the Navy Motion Picture Service 
Manual and applicable on-board standards. 



INTERIOR VOICE 
COMMUNICATIONS SYSTEM 

In earlier sections of this manual a variety 
of the conventional voice communications systems 
were covered. They may be classified as belonging 
to one of four basic groups: 

1. Sound-Powered Telephone Systems 

2. Dial Telephone Systems 

3. Intercommunication Systems (Intercom) 

4. Central Amplifier Announcing Systems 

These systems were originally designed in the 
1930's and 1940's to fulfill a specific communi- 
cations need. Each group has its own character- 
istics and each is better suited to support a 
particular shipboard evolution than are the other 
three. 

The systems which are members of these 
groups are reliable and as a rule provide adequate 



247 



SHIPBOARD ELECTRICAL SYSTEMS 



interior communications capabilities, tout have 
two major disadvantages. 

The first disadvantage is that each is designed 
to operate individually without provisions to 
interface with systems that possess different 
communications capabilities. Such systems re- 
quire that if a user is to have access to the 
capabilities of all four communication groups, 
he must have devices that provide him access 
to each group (i.e., a dial telephone, a IMC 
microphone control station, an intercommuni- 
cations unit, a sound-powered telephone, etc.). 

The second disadvantage is that individual 
wiring must be installed to a location for each 
system that the users are to have access to. 
Thus, as the communications needs of a location 
change, wiring changes must be made to add or 
delete the systems required. 

The Interior Voice Communications System 
(IVCS) is an integrated communications system 
that attempts to solve the shortcomings of older 
systems. IVCS combines the features of sound- 
powered telephones, dial telephones, and inter- 
communications units into one system and it 
can interface with other shipboard communi- 
cations systems. Additionally, IVCS provides 
features and services not available from any 
of the conventional shipboard communications 
systems. 

IVCS 

The IVCS, as installed on the new Landing 
Helicopter Assault (LHA) ships, is a computer- 
controlled circuit- switching voice communica- 
tions system. The IVCS consists of terminals 
(user access devices), accessories, and two 
computer- controlled Interior Communications 
Switching Centers (ICSC). Two ICSC's are used 
to provide redundancy and are so located that 
simultaneous damage to both is unlikely. 

Terminal Devices 

Two types of terminal devices (network 
terminal and dial terminal) are used with the 
IVCS. The type of terminal, the way it is 
connected into the system, and the computer 
program determine the type of service that is 
provided to each user. 

NETWORK TERMINAL. The network termi- 
nal (fig. 11-16) provides service comparable 
to that provided by sound-powered telephone 
systems. By depressing one of the four numbered 
pushbuttons, the user will be connected to any 



one of four networks. The networks are hard- 
wired circuits with a predetermined number of 
network terminals connected to them. The net- 
works are connected in a manner that is similar 
to sound-powered telephone string circuits. Each 
network circuit is also connected to one of the 
Interior Communications Switching Centers. The 
nature of this connection will be covered later 
when the IVCS organization is discussed. The 
network circuits are manned for certain ship- 
board evolutions, as sound-powered circuits 
would be on a ship equipped with conventional 
1C systems. 

DIAL TERMINAL. The dial terminal pro- 
vides service that can be most easily compared 
to that provided by a dial telephone system, 
The dial telephone terminals (fig. 11-17) are 
connected to the Interior Communications Switch- 
ing Centers (ICSC). They are used in a manner 
that is comparable to a commercial dial telephone 
with pushbutton dialing. 

TERMINAL AC C E SSORIE S. There are 
several types of accessories designed for use 
with the dial and network terminals. These 
accessories include headsets, handsets, spray- 
tight enclosures which permit the installation 
of the terminals in exposed areas, and loud- 
speaker units. 

The loudspeaker units (fig. 11-18) are designed 
for use with either the dial or the network termi- 
nals. Both the units illustrated in figure 11-18 
are equipped with press-to-talk switches. Addi- 
tionally, by depressing the hands free pushswitch 
on the unit pictured infigure 11-18B, the operator 
can communicate without using the press-to-talk 
switch. Both these accessories permit terminal 
users to communicate without either a handset 
or headset, providing user service that is com- 
parable to that provided by commercial speaker 
phone units. 

Interior Communications 
Switching Center (ICSC) 

The ICSC's are the heart of the IVCS. They 
perform the switching actions necessary to con- 
nect the calling party to the called party. In 
this manner the ICSC's are similar to the auto- 
matic switchboards of a dial telephone system* 
However, most similarity ends at this point 
because the design, construction, and wiring of 
the automatic telephone switchboard dictates 
the manner in which it will perform; changes 
to its performance can only be made by changing 



248 



Chapter 11 AMPLIFIED VOICE SYSTEMS 




27,398X 



Figure 11-16. Network terminal,, 



its physical characteristics. The switching 
mechanisms of the ICSC's, on the other hand, 
are controlled by a computer and its associated 
memory. The switching devices of the ICSC 
perform their operations in a prescribed manner 
because the computer instructs them to do so, 
not because it is physically impossible for them 
to perform in any other way. As an example: 
in dial telephone systems certain telephones 



may cut into the conversations of others or 
have other special features as a result of equip- 
ment modifications. In the IVCS special features 
are granted to a terminal on the basis of the 
information stored in the computer memory. If 
a terminal requires the capability of cutting in 
on the conversations of others, instructions 
are placed into the computer memory which 
permit it to do so. 



249 



SHIPBOARD ELECTRICAL SYSTEMS 




27.398X 



Figure 11-17. -Dial terminal. 



IVCS ORGANIZATION 

Figure 11-19 is a block diagram of the IVCS. 
As illustrated, the IVCS contains two ICSC's 
each of which operates independently of the other. 
Each ICSC receives 440 VAC power from the 
ship's distribution system. In addition, each 
ICSC is provided with standby battery supplies 
capable of supplying power to each ICSC for 
1 hour in the event ship's power is lost. The 



ICSC's are connected together by the trunk and 
net intertie lines which permit the terminals 
connected to one ICSC to communicate with 
the terminals connected to the other ICSC. The 
Emergency Throwover Operation (ETO) lines 
also connect the two ICSC's together. 

The ETO lines are part of a feature that 
allows an ICSC to provide service to a limited 
number of dial terminals normally assigned 
to the other ICSC. If the ICSC to which they 



250 



Chapter 11 AMPLIFIED VOICE SYSTEMS 




A. STANDARD LOUDSPEAKEfMJNIT 



HANDS FREE -INDICATOR LAMP 



HANDS FREE 
PUSHSWITCH 




Figure 11-18. Loudspeaker units. 



27.399 



SHIPBOARD ELECTRICAL SYSTEMS 




i 

CO 
O 



252 



Chapter 11 AMPLIFIED VOICE SYSTEMS 



are normally assigned fails, predesignated dial 
terminal^ are served Tby the other ICSC through 
the ETO lines. 

Approximately half of the dial and networks 
terminal devices of the IVCS are connected 
to each ICSC. 

The dial terminals of the IVCS are connected 
to the ICSC's in such a way that the dial commands 
originated by them may be processed by the 
computer. The computer then causes the switch- 
ing mechanisms to connect the calling party to 
the called party, unless it is restricted from 
doing so by the instructions contained within its 
memory. 

The network terminals of the IVCS are not 
connected to the switching mechanisms of the 
ICSC's in the same manner as the dial terminals. 
Network terminals cannot originate calls to 
other terminals or networks. They are, as stated 
before, connected to each other to form a network 
circuit that is similar to sound-powered telephone 
string circuits. Under normal circumstances 
network terminals can communicate with only 
those other terminals connected to the same 
network circuit. However, the network circuits 
are connected to the ICSC's in such a way that 
it is possible for certain dial terminals (desig- 
nated in the computer memory) to connect them- 
selves through the switching mechanisms to the 
network circuits. 



Interfaces 

As shown in figure 11-9, the dial terminals 
connected to each ICSC can interface with the 
following ship's systems or equipment: 

1. Ship's radio communications equipment 

2. Ship's central amplifier announcing sys- 
;ems (IMC, 2MC, SMC, etc.) 

3. Sdund-powered telephone circuits (Bridge 
;o Bridge, weapons, etc.) 

4. The manual telephone switchboard, which 
.s part of the IVCS, is comparable to the 
attendant's cabinet of a dial telephone system 
serves two functions: 

a. Inport: It permits the IVCS to interface 
vith up to eight shore telephone lines. 

b. At sea: It permits the IVCS to interface 
vith eight multichannel radio links that are used 
irimarily for amphibious operations by embarked 
Xlarines. 

5. Several short-range, two-way radios that 
,re specifically designated as the base stations 
or the Man-on-the-Move (MOM) Communications 



System. This is a special two-way radio com- 
munications system that consists of individual 
personal radio transceivers which provide, as 
the name implies, man-on-the-move communi- 
cation capabilities. The MOM transceivers are 
operated on one of the several radio frequencies 
designated specifically for them. By interfacing 
with the base stations, the IVCS make sit possible 
for a dial terminal user to be connected to one 
of the MOM radio networks and to communicate 
with personnel equipped with MOM transceivers. 
6. Although not actually an interface, the 
dial terminals may gain access to the network 
terminals of the IVCS through the switching 
mechanisms of the ICSC's. 

Not every dial terminal can gain access to 
the above listed systems or equipment. For 
instance, before a dial terminal can interface 
with the IMC, specific instructions must be 
contained within the memory of the computer 
which permits that individual terminal to inter- 
face with the IMC, In this way only those dial 
terminals that are specifically authorized may 
interface with any equipment or system* 

The ability to interface with other systems, 
as can be imagined, provides the IVCS user with 
communications capabilities that far exceed those 
of conventional interior communications systems. 
From one dial terminal it is possible to talk 
to someone in the next compartment or, through 
the ship's radio equipment it is possible to 
talk to someone on the other side of the world. 

Special Features 

The IVCS provides many special features, 
some of which are provided by conventional 1C 
systems, but many of which are unique to the 
IVCS. These special features are listed below. 

DUAL TONE MULTIFREQUENCY (DTMF) 
DIALING, The IVCS dial terminals utilize Dual 
Tone Multifrequency (DTMF) Dialing, which is 
comparable to the pushbutton dialing used by 
most commercial telephone companies. 
Normally, the IVCS terminals utilize four digit 
DTMF dialing. 

HUNT-THE-NOT-BUSY. The hunt-the-not- 
busy feature is not new, having been used in many 
dial telephone systems. However, the manner 
in which this feature is provided by the IVCS 
is new. In dial telephone systems, the attendant's 
cabinet is usually provided with the hunt-the- 
not-busy feature. For the attendant's cabinet 



253 



SHIPBOARD ELECTRICAL SYSTEMS 



to receive this service, wiring changes are 
made to a group of sequential numbers (usually 
237, 238, 239, 230). Having been modified, it 
is possible for a party to dial the first sequential 
number (237) and, if that number is already 
in use, the switching mechanisms of the auto- 
matic switchboard steps to the next higher idle 
sequential number (238, 239, 230). A busy signal 
is received by the calling station only if all 
the numbers in the group are busy. 

The automatic telephone system, because of 
equipment design, must use sequential numbers 
to provide the hunt-the-not-busy feature. The 
IVCS uses a stored program in memory and, 
therefore, any number can be programmed to 
belong to a hunt-the-not-busy group. For example, 
7142, 5237, and 7413 can be in a hunt-the-not- 
busy group. These numbers can easily be changed, 
simply by changing that portion of the memory 
that pertains to them. 



CONFERENCE CALL. -The conference call 
feature permits a dial terminal, which is author- 
ized in the system memory, to dial up to five 
other terminal numbers at the same time and 
set up a conference call. All six parties can 
then converse with one another. 



COMMAND NET. The command net feature 
permits a dial terminal, which is authorized 
in the system memory, to dial a special four- 
digit code. Dialing of this special code causes up 
to 30 predesignated (in memory) terminals to 
be rung at the same time. As the called terminals 
are answered, they join the command net and 
all parties can converse with each other. 



PRIVACY OVERRIDE. The privacy over- 
ride feature permits a dial terminal, which is 
authorized in the system memory, to complete 
a call whether or not the called terminal is 
busy. 

If a called terminal is busy, the override 
(OV) pushbutton is depressed on the dial terminal 
(fig. 11-17), and the number is redialed to permit 
the calling terminal to join the busy parties. 
A 1-second tone is generated and placed on the 
busy circuit to alert the persons on the busy 
circuit that someone has joined their conversa- 
tion. 



RING OVERRIDE. All dial terminals that do 
not have the privacy override feature will auto- 
matically have the ring override feature. 

If the called terminal is busy, the override 
(OV) pushbutton is depressed and the number 
is redialed. Three short tones are placed on 
the audio lines of the busy parties. These tones 
alert the busy terminals that someone is trying 
to call one of them. The busy terminals should 
then complete their conversation as quickly as 
possible and hang up to allow the other party 
to call. 



CALL FORWARDING. Call forwarding per- 
mits the user of a dial terminal, which is 
authorized in the system memory, to have his 
incoming calls forwarded to another terminal. 
For instance, the captain might be expecting an 
important call, but an appointment requires his 
presence in the wardroom. By dialing a special 
code the captain can instruct the computer to 
direct all his incoming calls to the wardroom. 
After these instructions are placed into the 
system, anyone dialing the captain's terminal 
will cause the wardroom terminal to ring. Upon 
returning to his cabin, the captain dials another 
code and cancels his call -forwarding instructions. 



ABBREVIATED ADDRESSING. Abbreviated 
addressing permits authorized dial terminals 
to call certain other terminals by depressing 
the (A) pushbutton (fig. 11-17) and one numerical 
pushbutton. The dial terminal that is to use 
abbreviated addressing designates up to 10 fre- 
quently called terminals in the system memory. 
By depressing the abbreviated address push- 
buttons, the calling terminal is connected to the 
called terminal. This feature, in conjunction 
with a loudspeaker accessory, provides user 
service that is similar to that provided by con- 
ventional intercom units. 



IVCS SUMMARY 

As you can see from the previous discussion, 
the IVCS offers many features and services not 
provided by the conventional interior communi- 
cations systems. The system described herein 
is presently planned for installation in LHA's 
only. Although these ships represent only a small 
part of the overall ships' population, more of 
these systems, or similar systems, will be 
installed in future ship types. 



254 



CHAPTER 12 

GYROCOMPASSES 



Gyrocompasses are devices which use the 
principle of a gyroscope to obtain an indication 
of true north. Gyrocompass systems develop 
own ship's heading and transmit information 
to various navigation and weapons stations and 
to other equipment throughout the ship. Gyro- 
compasses are identified by the mark-mod sys- 
tem. The mark (Mk) number designates a major 
development of a compass. The modification 
(Mod) number indicates a change to the major 
development. 

Gyrocompasses depend on the physical prop- 
erties of the spinning gyroscope and the effects 
of the earth* s gravity and rotation for their 
operation. In this chapter we shall discuss: 

(1) The basic gyroscopic principles as they 
apply to a functional gyrocompass system. 

(2) The basic operating principles of the 
Mk 23 and Mk 19 gyrocompasses. 

(3) Gyrocompass records and logs. 

You will find additional information in current 
editions of Synchro, Servo and Gyro Fundamentals, 
NAVEDTRA 10105; 1C Electrician 3&2, NAVEIP 
TRA 10558; 1C Electrician l&C. NAVEDTRA 
10557; and the manufacturer's manual for your 
specific installation. 



THE GYROSCOPE 

The gyroscope is a heavy wheel, or rotor, 
suspended so that its axle is free to turn in 
any direction. The rotor axle is supported in 
a ring by two bearings at S and S f , as illus- 
trated in figure 12-1. This ring is supported 
inside a slightly larger outer ring by studs 
and bearings at H and H f . The outer ring is 
mounted in the supporting frame by studs and 
"bearings at V and V f . The inner and outer 
rings are called gimbals. The supporting frame 



VERTICAL(TURN)- ' ** V 
AXIS 



HORIZONTAL (TILT) 
AXIS 




Figure 12-1. The gyroscope. 



77.194 



is not a part of the gyroscope but merely 
supports it. The rotor and the two gimbals are 
balanced about their axes. The axes are mutually 
perpendicular and intersect at the rotor's center 
of gravity. The bearings of the rotor at points 
S and S ! and the gimbals at points V, V f , H, 
and H 1 are considered to be completely free of 
friction. Actually, there is always some friction, 
but it has been reduced to such an extent that 
it is considered nonexistent. 



255 



SHIPBOARD ELECTRICAL SYSTEMS 



THREE DEGREES 
OF FREEDOM 

The gyroscope rotor has three degrees of 
freedom freedom to spin, freedom to turn, and 
freedom to tilt which permit the rotor to 
assume any position within the supporting frame 
(fig. 12-1). The rotor is free to spin about 
its own axle (spinning axis S-S') the first 
degree of freedom. The inner gimbal ring is 
free to tilt on its bearings about the horizontal 
axis (H-H T ) the second degree of freedom. 
The outer gimbal ring is free to turn on its 
bearings about the vertical axis (V-V f ) the 
third degree of freedom. 



GYROSCOPIC 
PROPERTIES 

When a gyroscope rotor is spinning rapidly, the 
gyroscope develops two properties rigidity of 
plane and precession which it does not have 
when the rotor is at rest. Rigidity of plane and 
precession together with the earth's gravity 
and rotation make it possible to convert a gyro- 
scope into a gyrocompass. 



Rigidity of Plane 



When the rotor of a gyroscope is set spinning 
with its axle pointed in one direction (fig. 12- 
2A), the rotor continues to spin with its spin 
axle pointing in the same direction, no matter 
how the supporting frame of the gyroscope is 
tilted or turned (fig. 12-2B). As long as the 
gimbal bearings are frictionless and the rotor 
spins, no amount of turning of the supporting 
frame can change the plane of the rotor with 
respect to space. This property of the gyro- 
scope is known as rigidity of plane, gyroscopic 
inertia, rigidity in space, or stability. It can 
be explained by Newton's first law of motion 
which states that a body in motion will continue 
to move at a constant speed in a straight line 
unless acted upon by an outside force. The 
rigidity of the gyroscope may be increased by 
(1) making the rotor heavier, (2) by causing the 
rotor to spin faster, or (3) by concentrating most 
of the rotor weight near its circumference. If 
two rotors with cross sections like those shown 
in figure 12-3 are of equal weight and rotate 
at the same speed, the rotor in figure 12-3A 




27.128(77A) 

Figure 12-2. Rigidity of plane of spinning 
gyroscope. 



will be less rigid than the rotor in figure 
12-3B. This condition exists because the weight 
of the rotor in figure 12-3B is concentrated 
near the circumference. Gyroscopes and gyro- 
compass rotors are both constructed with most 
of their weight concentrated near the circum- 
ference. 



256 



Chapter 12 GYROCOMPASSES 





(A) 



77.196 
igure 12-3. Weight distribution in rotors. 

^cession 

As previously stated, because of rigidity of 

ne, movements of the supporting frame have 

effect on the direction in which the spin 

e of a spinning gyroscope points. To change 



the direction in which the axle points, you must 
apply a force to the gyroscope rotor about its 
spin axis. A downward force on one end of the 
rotor axle attempts to tilt the gyroscope about 
the horizontal axis and, if the rotor is not 
spinning, the axle will tilt in response to the 
force. However, if the rotor is spinning, as in 
figure 12-4A, its rigidity will resist any attempt 
to tilt the rotor about the horizontal axis and, 
instead, the gyroscope will precess about the 
vertical axis. Any force (F) attempting to turn 
the spinning gyroscope about the vertical axis 
is similarly resisted and results in precession 
(P) about the horizontal axis (fig. 12-4B). 

Any force that tends to change the plane of 
rotation causes a gyroscope to precess. Pre- 
cession continues as long as there is a com- 
ponent of force acting to change the plane of 
rotation, and precession ceases immediately 
when the force is removed. 

If the plane in which the force acts moves 
at the same rate and in the same direction as 
the precession which it causes, the precession 
will be continuous. This is illustrated by figure 
12-5 in which a weight W representing an un- 
balanced condition about the horizontal axis is 




'--HORIZONTAL- 
AXIS 




PRECESSION 



ABOUT THE VERTICAL 
AXIS 
A 



PRECESSION ABOUT THE 
HORIZONTAL AXIS 
B 



27.131 



Figure 12-4. Precession. 
257 



SHIPBOARD ELECTRICAL SYSTEMS 



i S' 




77.197 



Figure 12-5. Continuous precession. 



suspended from the end of the spin axle Al- 
though the weight is exerting a downward force, 
it must be remembered that the force itproduces 
against the particles in the spinning wheel is 
horizontal. This force is imparted to the par- 
ticles in the wheel as exemplified by arrows 
F and F T . If the wheel rotates clockwise as 
seen from the weighted end, precession will 
occur in the direction of arrow P. As the 
gyroscope precesses, it carries the weight around 
with it so that forces F and F ? continuously act 



at right angles to the plane of rotation, and pre- 
cession continues indefinitely. 

A simple way to determine the direction of 
precession is illustrated in figure 12-6. Con- 
sider the force that tends to change the plane 
of rotation of the rotor as it is applied to 
point A at the top of the wheel. This point does 
not move in the direction of the applied force, 
but a point displaced 90 in the direction of 
rotation moves in the direction of the applied 
force. This is the direction of precession. 

Forces of Translation 

Whereas, forces which attempt to turn and 
tilt a gyroscope cause precession, forces which 
act in a straight line through the center of 
gravity of a gyroscope will not cause precession 
and are known as forces of translation. Forces 
which produce precession may be classified 
as twisting forces or torques which act about 
either the vertical or horizontal, or both the 
vertical and horizontal axes. Forces of translation 
do not impart a twisting force or torque about 
any axes, but, to repeat, they act in a straight 
line through the center of gravity of the gyro- 
scope. Referring back to figure 12-1, you can see 
that the gyroscope is suspended by gimbal rings 
in such a way that the spin, vertical, and hori- 
zontal axes bisect at a point that also coincides 
with the gyroscope 's center of gravity. Any force 
acting in a straight line along one of these axes or 
any force acting simultaneously along two or all 
three of the axes is a force of translation and 



LJ _,.__. 




27.131(77A) 
Figure 12-6. Direction of precession. 



258 



Chapter 12 GYROCOMPASSES 



will not cause precession. Thus the base and 
gimbaling system of the gyroscope provide it with 
not only the three freedoms but also permit the 
gyro to be moved as a unit in any direction 
without causing precession. 

EFFECT OF EARTH'S 
ROTATION 

As explained previously, a spinning gyroscope 
can be moved in any direction without altering 
the angle of its plane of rotation. If the base of 
a free-spinning gyroscope were placed on the 
earth's surface at the equator with the spinning 
axis of the gyroscope horizontal and aligned 
east and west, an observer in space above the 
north pole (fig. 12-7) would note that the earth 
rotates counterclockwise from west to east and 
carries the gyroscope along. As the earth rotates, 
rigidity of plane keeps the gyroscope's spin axle 
pointed in the same direction at all times. 
Assume that the gyroscope is set spinning at 
0000 hours with its spinning axis aligned east 
and west and parallel to the earth's surface. At 
0600, 6 hours after the gyroscope was started, 
the earth has rotated 90 but the axle of the 
gyroscope is still aligned as before. At 1200 
the earth has rotated 180 while the gyroscope 
retains its original alignment. At 1800 the earth 
has rotated 270 while the gyroscope still retains 




its original alignment. At 0000 the earth has 
rotated 360, the gyroscope has returned to 
its original starting position, and throughout 
the 24-hour period the alignment of the spin 
axle of the rotor has remained constant. 

The effects of rigidity of plane described 
above appear quite differently to an observer 
standing on the earth's surface. As the earth 
rotates, the observer moves with it, and the 
gyroscope wheel appears to rotate about its 
horizontal axis. Figure 12-8 shows how this 
spinning gyroscope is placed on the earth's 
surface at the equator at 0000 hours with the 
darkened end of the spinning axis horizontal and 
pointing toward the observer. At 0600, 6 hours 
after the gyroscope was started, the earth has 
rotated 90 and the gyroscope axle apparently 
has tilted. To the observer, the darkened end 
of the axle points straight up and is vertical 
to the earth's surface. At 1200 the darkened 
end of the gyroscope axle is horizontal again, 
but it now points away from the observer. 
At 1800 the darkened end of the gyroscope 
axle is again vertical and points straight down. 
At 0000 the earth has rotated 360 and the 
gyroscope appears to the observer to be back 
in its original position while, in fact, it has 
been fixed in space for the entire period. 

The rotation of the gyroscope axle as seen 
by the observer on the earth's surface is known 





12.144(77A)A 

Figure 12-7. Free gyroscope at the equator 
viewed from space above the north pole. 



12.144(77A)B 

Figure 12-8. Spinning gyroscope at the equator 
viewed from the earth's surface. 



259 



SHIPBOARD ELECTRICAL SYSTEMS 



as apparent rotation. Apparent rotation is caused 
by rigidity of plane which maintains the plane 
of the gyroscope wheel parallel to its original 
position in space. The apparent rotation that 
makes a gyro appear to tilt albout the hori- 
zontal axis is referred to as horizontal earth 
rate (H.E.R.) effect. This effect varies with 
the cosine of the latitude and is maximum at 
the equator and zero at the poles. 

Now assume that the spinning gyroscope, 
with its spinning axis horizontal, is moved to 
the north pole (fig. 12-9). To an observer in 
space above the north pole, the gyroscope axle 
remains fixed and the earth rotates under it. 
To an observer on the earth's surface, the 
gyroscope appears to rotate about its vertical 
axis. This apparent rotation about the vertical 
axis is referred to as vertical earth rate (V.E.R.) 
effect, and it varies with the sine of the latitude. 
It is maximum at the poles and zero at the 
equator. 

When the spin axis of the gyroscope is 
aligned so that it is parallel to the earth's 
spin axis, apparent rotation will take place 
around the gyroscope's spin axis and it cannot 
be readily observed. 

When placed at any point between the equator 
and either pole, a gyroscope whose spinning axis 



is not parallel to the earth's spinning axis 
has an apparent rotation that is a combination 
of horizontal earth rate and vertical earth rate. 
The combined earth rate effects at this point 
make the gyroscope appear to rotate partly 
about the horizontal axis and partly about the 
vertical axis. The H.E.R. causes the gyro to 
appear to tilt about its horizontal axis and the 
V.E.R. causes the gyroscope to appear to turn 
about its vertical axis. The magnitude of the 
apparent turn or tilt is dependent on the latitude 
where the gyroscope is located. At latitudes 
near the equator, the gyro appears to tilt more 
than turn. At latitudes near either pole the gyro 
appears to turn more than tilt. This apparent 
rotation is illustrated in figure 12-10 by a 
spinning gyroscope with its spin axis pointed 
north and parallel to the earth's surface at 
45 N latitude. To an observer on the earth's 
surface, the gyroscope appears to both turn 
and tilt. 

To summarize, a gyroscope, if set on any 
part of the earth 1 s surface with its spinning 
axis not parallel to the earth's spin axis will 
appear to rotate. The H.E.R,, which is maxi- 
mum at the equator and zero at the poles, 
causes the gyroscope to appear to tilt about its 



APPARENT ROTATION 



VERTICAL 
AXIS 




EARTHS 
ROTATION 



77.198 

Figure 12-9. A gyroscope with its spin axis set 
horizontal at the north pole; observed from a 
point in space beyond the equator. 




77.199(140B) 

Figure 12-10. Apparent rotation of a gyroscope 
at 45N latitude. 



260 



Chapter 12 GYROCOMPASSES 



horizontal axis. The V.E.R., which is zero at 
the equator and maximum at the poles, causes 
the gyroscope to appear to turn about its vertical 
axis. At any latitude between (equator) and 
90N or 90S (north or south poles), the apparent 
rotation of the gyroscope will take place about 
the horizontal and vertical axes simultaneously. 



MAKING THE GYROSCOPE 
INTO A GYROCOMPASS 

We have discussed the properties of the simple 
gyroscope and the effects of the earth's rotation 
upon it. Now, let us investigate the manner in 
which rigidity of plane and precession plus the 
effects of horizontal earth rate and gravity 
may be used to make a simple gyroscope align 
its spin axis north- south and maintain that align- 
ment. 

Before the simple gyroscope is converted 
into a gyrocompass, its base and gimbaling 
rings (as shown in fig. 12-1) will be changed 
as shown in figure 12-11 A. The simple gyro- 
scope is modified by replacing the inner gimbal 
with a sphere or case, a feature of all gyro- 
compasses which serves to protect the rotor. 
Also, the base has been replaced by a phantom 
ring, or phantom. The phantom differs from 
the base of a simple gyroscope in that the base 
of the simple gyroscope is stationary, whereas, 
the phantom of the modified gyroscope is driven 
Tby a servomechanism (not shown) so that it is 
maintained in alignment with the spin axis of 



the gyroscope. The servomechanism that drives 
the phantom also positions the compass card and 
the synchro transmitters which provide indi- 
cations of own ship's heading (OSH). Look again 
at figure 12-11 A. The gyrosphere of the modi- 
fied gyroscope provides the rotor with the free- 
dom to spin. The vertical ring provides the 
gyrosphere with the freedom to turn; the vertical 
ring is suspended from the phantom so that it 
is free to tilt, and the phantom is maintained 
in alignment with the spin axis of the gyro- 
scope by a servomechanism. Further, to become 
a gyrocompass the gyro must be modified so 
that it can: 

1. Align its axis on the north- south plane 
(meridian) 

2. Align its axis nearly horizontal 

3. Maintain its alignment horizontally and on 
the meridian, once attained. 

SEEKING THE 
MERIDIAN 

The first step in making the modified gyro- 
scope into a gyrocompass is to make the gyro 
seek the meridian. To do this, a weight W 
is added to the bottom of the vertical ring as 
shown in figure 12-11B. This weight causes 
the previously balanced gyro rotor/vertical ring 
assembly to become unbalanced about its hori- 
zontal axis, being heavier at the bottom than at 
the top. The modified gyroscope and weight 
are placed at the equator with the gyroscope 



VERTICAL 
RING 



GYRO ROTOR 



GYROSPHERE 




PHANTOM 



VERTICAL 
RING 



GYRO ROTOR 
GYROSPHERE 




PHANTOM 



27.135:136 



Figure 12-11. A. Modified gyroscope. B. Modified gyroscope with weight. 

261 



SHIPBOARD ELECTRICAL SYSTEMS 



spin axis horizontal, pointing east-west, and 
the rotor spinning clockwise as viewed from 
the west (point A, fig. 12-12A and 12-12B). 
As the earth rotates, the east end of the gyro- 
scope spin axis rises in relation to the earth's 
surface (point B, fig. 12-1 2A and 12-12B). This 
action is the result of rigidity of plane, which 
causes the gyroscope to point in the same 
direction, and H.E.R., which causes the gyro to 
appear to tilt about its horizontal axis in relation 



to the earth's surface. As the gyro and vertical 
ring appear to tilt, the weight W rises against 
the pull of gravity. The earth's gravity acts 
against the weight and causes a torque to be 
applied about the horizontal axis of the gyro- 
scope. This torque causes the gyroscope to 
precess about its vertical axis in the direction 
indicated at point C in figures 12-12A and 
12-12B; the gyroscope spin axis then has moved 
and the spin axis is no longer aligned east-west. 



VERTICAL 
RING 



GYRO ROTOR 




ASSUME EXTERNAL MEANS 
ARE PROVIDED TO TURN 
PHANTOM SO AS TO FOLLOW 
THE GYRO IN AZIMUTH. 







Figure 12-12. Effect of weight and earth's rotation on the gyroscope. 

262 



27.137 



Chapter 12 GYROCOMPASSES 



As the end of the gyroscope which was first 
pointing east (which will now Tbe referred to as 
the north end) continues to rise due to the H.E.R., 
the torque on the gyro caused by the weight 
Tbecomes greater since the moment arm through 
which the weight acts gets longer due to the 
greater tilt. As the speed of precession is 
directly related to the torque, the gyroscope 
turns about its vertical axis as shown at point 
D, figures 12-12A and 12-12B at an increasing 
speed until the axis is on the meridian (aligned 
north- south as shown at point E of figures 
12-12A and 12-12B. 

At point E of figures 12-12A and 12-12B, 
the gyroscope is aligned north- south, but the 
tilt, the torque caused by the tilt and the weight 
W, and the speed of precession are all at 
maximum; therefore, the gyroscope continues to 
precess past the meridian. As the north end of the 
gyroscope's spin axis crosses the meridian, the 
H.E.R. acts upon it and causes the tilt to start 
decreasing. As the tilt decreases, the rate of 
precession decreases. Finally, as a result of 
the H.E.R. the axle becomes horizontal and, 
since the weight on the vertical ring no longer 
produces a torque, precession stops. At this 
point (point F of figure 12-12B), the north 
axle has precessed as far west of the meridian 
as it was originally to the east of the meridian 
(point A of fig. 12B). 

As the earth continues to rotate, the north 
end of the gyroscope spin axis starts to fall. 
The weight is raised against the forces of gravity 
on the opposite side of the gyroscope's hori- 
zontal axis, causing the gyroscope to precess 
back toward the meridian. When the gyroscope 
reaches the meridian (point G of fig. 12-12B), 
its north axle is tilted downward to a maximum 
degree and the torque from the weight cause it 
to precess past the meridian. As the north 
axle once again processes to the east of the 
meridian, the H.E.R. starts to reduce the tilt. 
Finally, the gyroscope precesses back to its 
original starting point (point A of fig, 12-12B), 
while the H.E.R. has caused the north axle 
to be once again level with the earth's surface. 
At this point the gyroscope's north axle has 
completed one complete cycle, but H.E.R. con- 
tinues to affect the gyro and causes its north 
axle to once again start to rise, and the weight 
causes the gyro to precess from east back toward 
the meridian (north). This cycle will repeat 
itself indefinitely with the gyroscope oscillating 
back and forth across the meridian from east 
to west and back again to the east. 



By hanging a weight on the vertical ring of the 
gyroscope, the first requirement for making a 
gyroscope into a gyrocompass making the gyro 
axle seek the meridian has been fulfilled. How- 
ever, some means must be provided to suppress 
the oscillations so the gyro wheel will quickly 
come to rest with its axle level in the north-south 
position. 



SETTLING ON 
THE MERIDIAN 

To suppress the oscillations of the gyro 
about the meridian a small weight is added 
to the sphere in which the gyro is housed. This 
weight (Wi) is placed on the east side of the 
gyrosphere in the position shown in figure 12-13. 
With the gyro spin axis level, the force produced 
by gravity acting upon weight W^ and the gyro- 
scope's vertical axis are perpendicular to the 
earth's surface and parallel to each other; 
therefore, no torque is exerted about the gyro- 
scope's vertical axis by W 1% However, when the 
gyro tilts, due to H.E.R , the vertical axis of the 
gyroscope is no longer perpendicular to the 
earth's surface, and the force of gravity acting 
on Wi imparts a torque about the vertical axis 
of the gyroscope. The torque about the gyro- 
scope's vertical axis causes the gyroscope to 
precess about its horizontal axis. The net result 
of Wi is to cause the gyroscope to precess about 



VERTICAL 
RING 



GYRO ROTOR 

WEIGHT W, 



GYROSPHERE 

WEIGHT 
W 




PHANTOM 



27.138 

Figure 12-13. Gyroscope with weights on the 
vertical ring and sphere. 



263 



SHIPBOARD ELECTRICAL SYSTEMS 



its horizontal axis in a direction that opposes 
the tilt caused by the effects of H E.R. 

Now, when placed on the equator aligned 
east-west, as a result of the leveling action of 
weight Wi, the gyro axle is not tilted upward 
as much when it reaches the meridian as it 
was with only weight W. Since the gyro axle 
is not tilted as much, the torque produced by 
weight W is not so great. Therefore, the gyro 
axle will not precess as far to the west of the 
meridian as it was east of the meridian when it 
was started. 

After reaching the point where the axle is 
level and as far west of the meridian as it is 
going due to the action of weights W and Wj, 
the H.E.R. is still causing the axle to tilt 
downward. As a result, the forces due to the 
weights are reversed, and torques are created 
which precess the gyro to the east and upward. 
The same action takes place in the reverse 
direction. The gyro is not precessed as far to 
the east as it was to the west. Thus, the added 



weight Wj causes the ellipse to be reduced 
each successive oscillation; the north end of the 
gyro axle will follow a spiral path as shown in 
figure 12-14 instead of the previous elliptical 
path. 

A careful observation of the action of the two 
weights makes it apparent that the only position 
of rest that the gyro can find is with the gyro 
axle horizontal and on the meridian. In other 
words, the free gyroscope has been converted 
into a true north-indicating gyrocompass. 

An instrument such as the one we have 
described will indicate true north accurately as 
long as it is located at the equator and is not 
transported over the surface of the earth. When 
this compass is relocated to a latitude other than 
the equator, the V.E.R., which was zero at the 
equator, will then affect the gyro and cause it 
to turn away from the meridian. When the 
gyrocompass is transported across the surface 



GYRO COMPASS SETTLING 




27.139 



Figure 12-14. Effect of weights W and W^ on the gyroscope. 

264 



Chapter 12 GYROCOMPASSES 



of the earth, accelerations on the weights will 
cause torques on the gyro and precess it away 
from the meridian. 

Many other outside forces affect the gyro- 
compass causing it to indicate directions (gyro 
errors) other than true north. The different 
types of gyrocompasses employed by the Navy 
compensate for or eliminate gyro errors in 
different ways. Some of the forces which pro- 
duce errors may not affect a particular type 
of gyrocompass because the design of the com- 
pass negates the forces which produce certain 
errors. The other errors that cannot be elimi- 
nated are compensated for in different ways 
in different compass systems. 

In the older mechanical compasses the errors 
that cannot be eliminated* through design or 
adjustment, are corrected by precalculating the 
error for a given set of conditions and, then, 
simply by shifting the lubber's line that amount 
necessary to correct the error. In other words, 
the spin axis of the older mechanical compass 
is very seldom exactly aligned on the meridian 
(true north), but rather is pointed to some 
location a few degrees either east or west 
of the meridian. Mechanical devices on the 
compass are used to crank in corrections to the 
compass for the forces that are causing the 
errors. The mechanical devices then shift the 
lubber's line (correct the compass) so that 
the compass indicates as though the spin axis 
were truly aligned on the meridian. 

The electrical compasses take an entirely 
different approach to produce an accurate indi- 
cation of true north. 

The electrical gyrocompass uses an electronic 
control system to make it seek and indicate 
true north, vice the weights used on the simple 
gyrocompass. The force of gravity combined 
with the tilt of the gyro rotor as a consequence 
of H.E.R. are used as the controlling factors, 
as they were with the simple gyrocompass. 
However, instead of being used directly to con- 
trol the compass, the force of gravity acts on 
a special device that generates an electrical 
signal that is proportional to the tilt of the 
gyro rotor. The signal from the device is ampli- 
fied and used to apply torques electrically about 
the horizontal and vertical axes of the gyro- 
compass, and to cause the gyro's spin axis to 
settle on the meridian and level. 

Devices within the electrical compass develop 
an electrical signal that produces a torque 
on the gyrosphere which is equal and opposite 
to those factors that would cause errors. In 



this way, the gyrosphere of the electrical com- 
pass is maintained level and on the meridian 
continuously. 

The Mk 19 and Mk 23 are the electrical 
gyrocompasses which are rapidly replacing the 
mechanical compasses. They comprise the 
majority of the gyrocompass systems employed 
on Navy ships. In the next section of this chapter 
we shall discuss briefly the Mk 23 and Mk 19 
gyrocompass systems, their principles of 
operation, capabilities, and nomenclature. 



MK 23 GYROCOMPASS 

The Mk 23 gyrocompass is a small electrical 
compass capable of withstanding severe operating 
conditions without sacrificing its primary function 
of furnishing heading data that is accurate enough 
for navigational purposes. The Mk 23 gyrocompass 
is used as the master compass on many of the 
patrol-type combatant vessels and on many of 
the larger auxiliary vessels. It is also some- 
times used as a backup compass on some of the 
larger combatant ships, 

MK 23 GYROCOMPASS 
PRINCIPLES OF OPERATION 

Since the Mk 23 gyrocompass is an electrical 
compass, the force of gravity does not act 
directly on the gyro to make it align its spin 
axis on the meridian (north- south). For operation 
the Mk 23 relies on the gravity reference system, 
the followup system, and features that allow for 
correction of errors. 

Gravity Reference System 

The Mk 23 gyrocompass employs a special 
type level as its gravity reference system. The 
level, usually referred to as the electrolytic 
level, is similar to a carpenter's spirit level, 
except that it produces an electrical signal 
when not level with the earth's surface. As 
shown in figure 12-15, the level is attached 
to the vertical ring in such a way that it is 
parallel with the gyro's spin axis. Therefore, 
whenever the gyro's spin axis is not level 
with respect to the earth's surface, an electrical 
signal, which is proportional to the gyro's tilt, 
is produced by the electrolytic level. 

The tilt signal from the electrolytic level is 
amplified and applied to the torquers, which 
magnetically apply torques about the gyrosphere' s 
vertical and horizontal axes and cause precession. 



265 



SHIPBOARD ELECTRICAL SYSTEMS 



COMPASS TILT SIGNAL 




PHANTOM 



AZIMUTH 
TORQUE R 



Figure 12-15. Simplified diagram of electrical azimuth and leveling controls. 



7.170 



The torquer (fig. 12-15) located about the gyro- 
sphere's horizontal axis is known as the azimuth 
torquer. It applies a torque about the gyro- 
sphere's horizontal axis proportional to the 
amount of tilt (detected by the electrolytic level) 
of the spin axis and causes the gyrosphere to 
precess in azimuth. The effect of this torque 
is the same as that produced by the weight W 
of the basic gyrocompass discussed earlier. 
When one end of the gyro axis is tilted upward, 
the resulting torque about the horizontal axis 
precesses the gyro in azimuth. 

The leveling torquer, located about the vertical 
axis of the gyro (fig. 12-15), applies a torque 
about the vertical axis proportional to the tilt 
of the gyro spin axis (detected by the electro- 
lytic level) and causes the gyro to precess 
about the horizontal axis to reduce the amount 
of tilt. The effect of the leveling is the same 
as that produced by weight Wi attached to the 
east side of the gyrosphere of the basic gyro- 
compass. When one end of the gyro is tilted 
upward, the resulting torque, from the leveling 
torquer, about the vertical axis precesses the 
high end downward,, The gravity reference system 
(level, amplifiers, and torquers) of the Mk 23 
gyrocompass causes the compass to align itself 
with the meridian and permits elimination of the 
heavy weights used on the basic gyrocompass. 



Recall that, when the basic compass was 
moved, the weights were acted upon by accelera- 
tions which caused errors in the gyro. The 
gravity reference system Df the Mk 23 permits 
the gyrosphere and vertical ring to be perfectly 
balanced about the horizontal and vertical axes. 
Further, the vertical ring and gyrosphere are 
suspended in oil; their weight is adjusted so 
that they are weightless and balanced about both 
axes in the oil. Since the gyrosphere and vertical 
ring of the Mk 23 gyrocompass are weightless 
and balanced, they are not affected by the ac- 
celerations as was the basic gyrocompass. 

The Mk 23 gyrocompass, described thus far, 
aligns itself on the meridian and is free from 
errors caused by accelerations on the gyro- 
sphere. Still a better method of support must 
be devised and other errors must be corrected 
for before this compass is suitable for use 
aboard ship. 

Followup System 

Before the compass pictured in figure 12-15 
is installed aboard a ship, a better means of 
supporting it must be devised. As we begin 
the discussion of the followup system of the 
Mk 23 gyrocompass, remember that the gyro- 
compass remains fixed in space, pointing con- 
stantly in the same direction (north) and that 



266 



Chapter 12 GYROCOMPASSES 



the ship, in turning, rolling, etc., moves under 
the gyro. 

The gyro pictured in figure 12-15 will function 
as long as its spin axis is aligned parallel with 
the ship's centerline and the ship is on a due 
north or south heading. In this case the ship's 
rolling motions will take place about the spin 
axis of the gyro, and the pitching motion of the 
ship will take place albout the gyro's horizontal 
axis. As the ship turns to an easterly or westerly 
heading, the phantom and vertical ring will move 
with the ship while the gyrosphere will continue 
to point north. On a due east heading, the pitching 
motion of the ship would still take place about 
the gyro's horizontal axis, however, the rolling 
motion of the ship would now take place about 
the gyro's vertical axis. Any rolling motion of 
the ship would transmit torques through the 
vertical axis and cause the gyro to precess off 
the meridian. 

The gyro we have just described has essentially 
lost one of its degrees of freedom (freedom 
to tilt) and can no longer be effective as a gyro- 
compass. 

Also, for the gyrocompass to be useful, 
some method must be provided for indicating 
the ship's heading relative to true north and 



for transmitting this indication to the remote 
gyrocompass repeaters. If a data transmitting 
device (synchro) were to be attached directly 
to the gyrosphere to provide this information, 
the accuracy of the compass would be seriously 
impaired, if not destroyed. Such a data trans- 
mitting device would exert a torque on the gyro- 
sphere, and cause precession of the gyrocompass 
off the meridian. 

Both the above problems may be solved by 
using a followup system (fig. 12-16) to keep the 
phantom element aligned with the gyrosphere. 
As the ship turns under the gyrosphere, the 
phantom is kept in perfect alignment with the 
gyrosphere and in doing so the gyro retains its 
three degrees of freedom (spin, turn, and tilt). 
An electromagnetic device, called a followup 
pickoff f is attached to the vertical ring to detect 
any misalignment between the gyrosphere and 
the vertical ring. The followup pickoff emits 
an electrical signal proportional to the dis- 
placement. After amplification the signal drives 
a followup motor which repositions the phantom 
and vertical ring in respect to the gyrosphere 
and maintains them in alignment. In driving 
the phantom and vertical ring, the followup 



VERTICAL 
RING 



GYRO ROTOR 

FOLLOWUP PICKOFF 



GYROSPHERE 



SPIDER 
(FIXED TO SHIP BY GIMBALS) 




HEADING 

SYNCHRO 

TRANSMITTER 



7.174 



Figure 12-16. Simplified diagram of followup controls. 

267 



SHIPBOARD ELECTRICAL SYSTEMS 



motor also positions the heading synchro trans- 
mitters. Thus, the heading data is provided 
without causing precession to the gyrocompass. 
With the addition of the follomtp system, 
another means of supporting the gyrosphere, 
vertical ring, and phantom must Tbe provided. 
This support, called a spider, is attached to 
the ship through gimbal rings (not shown in 
figure 12-16). Both the followup motor and the 
heading synchro transmitters are mounted on 
the spider. The gimbals support the spider 
in such a way that it remains level with the 
earth's surface regardless of the rolling and 
pitching motions of the ship. 

Mk 23 Gyrocompass 
Errors and Correction 

At points on the earth's surface (other than 
the equator) and aboard ships which are moving 
(not accelerations, but movement), certain factors 
are introduced which will result in errors if 
they are not compensated for or negated by the 
design of the compass. 

VERTICAL EARTH RATE ERROR, If a gyro- 
compass is placed on the meridian and level 
in northern latitudes, apparent rotation resulting 
from V.E.R., which is zero at the equator, will 
cause the gyro to turn about its vertical axis 
and point to the east of the meridian. Apparent 
rotation resulting from H.E.R., which has no 
effect on the gyro as long as it is on the meridian, 
will cause the gyro's north end to rise as soon 
as the gyro spin axle was out of plane with the 
meridian. The resulting tilt signal from the 
electrolytic level will be amplified, and the 
torquers will apply torques about the gyro- 
sphere's vertical and horizontal axes to reduce 
the tilt and precess the gyro back to the meridian. 

There are four factors causing motion of the 
gyro as just described. V.E.R., H.E.R., the level- 
ing torquer, and the azimuth torquer. The V.E.R. 
and H.E.R. cause the gyro to turn away (error) 
from the meridian and unlevel it; they are con- 
stant factors for any given latitude. The second 
two factors, the leveling torquer and the azimuth 
torquer, attempt to precess the gyro back to the 
meridian and level it. The two torquers are 
actuated as a result of the tilt signal and depend 
upon it for their operation. As the torquers 
precess the gyro back toward the meridian, and 
as it approaches level, the tilt signal decreases. 
The decrease in tilt signal reduces the p re- 
cessional force exerted by the torquers and, at 
some point before the gyro is precessed back 



to the meridian and level, the precession forces 
exerted by the torquers exactly balance the 
apparent movement of the gyro caused by the 
V.E.R. and the H.E.R. As a result, the gyro 
spin axis will settle with its north end up and 
to the east of the meridian in northern latitudes, 
and it will settle with the north end down and to 
the west in southern latitudes. 

As the gyro is moved further north, the 
apparent rotation resulting from V.E.R. (maxi- 
mum at the poles and zero at the equator) in- 
creases. Consequently, the gyro settles further 
to the east. 

The small angle from the meridian at which 
the gyro axle settles varies with latitude. For 
this reason, a correction must be made to com- 
pensate for this error at any latitude where the 
compass may be used. 

To prevent the occurrence of such an error, 
an adjustable electrical signal, proportional to 
the V.E.R. at the latitude where the gyro is 
located, is applied continuously to the azimuth 
control torquer, as shown in figure 12-17. This 
causes a precession of the compass at a rate 
exactly equal but opposite to that of the V.E.R. 
The compass with this signal will settle level 
on the true meridian and will remain so. 

SPEED (MOVEMENT) ERROR. When a gyro- 
compass is placed aboard a ship which is sailing 
a northerly course, the north end of the gyro 
which, because of rigidity, tends to remain 
fixed in space, will appear to tilt upward in 
relation to the earth's surface. For a practical 
test of this observation, point a pencil at a 
distant object and move the pencil over the 
surface of a ball. As you move the pencil in 
a direction simulating a northerly course, the 
north end of the pencil will appear to rise 
in relation to the surface of the ball. Con- 
versely, if you move the pencil in a direction 
simulating a southerly course, the north end 
of the pencil will appear to fall. 

The rate at which the gyro axle will tilt 
depends on the speed and direction of the vessel. 
For any given speed the tilt effect will increase 
as the course traveled becomes more northerly 
or more southerly. Any component of northerly 
or southerly speed will produce the effects listed 
above. There will be NO tilting of the gyro axle 
ONLY when the ship's course is due east or 
west because, only then, will the ship's velocity 
be entirely at right angles to the spin axis of 
the gyrorotor. 

This tilting of the gyro spin axis, caused 
by traveling a northerly or a southerly course, 



268 



Chapter 



BALANCE 

COMPENSATION 

SIGNAL 



COMPASS TILT SIGNAL 



LEVELING 

.CONTROL 

AMPL 



AZIMUTH 
CONTROL 
AMPL 



VERTICAL 
RING 



LEVELING 
TORQUER 



GYRO ROTOR 

FOLLOWUP PICKOFF 



SPIDER 

(FIXED TO SHIP 

BY GIMBALS) 



VERTICAL 

EARTH 

RATE 

CORRECTION 
SIGNAL 



FOLLOWUP 

CONTROL 

AMPL. 



AZIMUTH CONTROL 

TORQUER 



FOLLOWUP 
MOTOR 



SPEED RESOLVER 



NORTH/SOUTH SPEED 



HEADING SYNCHRO 
TRANSMITTER 



HEADING DATA 




LATITUDE 
KNOB 



Figure 12-17. Simplified diagram of all controls for the Mk 23 gyrocompass. 



7.170 



affects the accuracy of the compass because 
the resulting tilt signal is amplified and applied 
to the torquers. For a northerly course the 
torquers precess the gyro off the meridian to 
its west, resulting in a westerly error. For a 
southerly course, the tilt signal from the level 
causes the gyro to be precessed to the east of 
the meridian resulting in an easterly error. 
If a torque were applied to precess the gyro 
axle downward at a rate equal and opposite to 
that which northerly or southerly speed is causing 
it to rise, the gyro would remain level and no 
azimuth error would occur. 



The gyro error resulting from ship's northerly 
or southerly speed is eliminated in the Mk 23 
gyrocompass, as shown in figure 12-17. An 
electrical signal proportional to ship's speed 
is furnished to the speed resolver, which is 
mounted on the spider, and the shaft of the 
resolver is positioned by the followup system, 
The resolver then resolves the electrical speed 
signal with the mechanical course input to pro- 
duce an electrical signal equal to ship's speed 
multiplied by the cosine of the course, or north/ 
south speed. The north/south speed signal is 
then applied to the leveling torquer to precess 



269 



SHIPBOARD ELECTRICAL SYSTEMS 



the gyro downward at the same rate at which 
it is trying to rise due to the northerly or 
southerly speed. By correcting the gyro in this 
manner, there will toe no azimuth error due to 
northerly or southerly speed, and the compass 
will remain level and on the meridian. 

CONSTANT HORIZONTAL TORQUE 
ERROR. Any constant torque about the hori- 
zontal axis of the gyro, such as that caused 
toy an unbalance of the gyrosphere and vertical 
ring, will cause the gyro to settle with a tilt 
and an azimuth error. As stated previously, 
the gyrosphere and vertical ring are suspended 
in oil; weights are added or removed from the 
gyrosphere and vertical ring until they are 
weightless and toalanced atoout their axes in the 
oil. However, it is very difficult to completely 
toalance the gyrosphere and vertical ring in the 
suspending oil. 

In the Mk 23 gyrocompass any torques resulting 
from the remaining unbalances can toe eliminated 
toy applying a variatole electrical signal to the 
azimuth torquer so that the torquer produces 
a torque that is equal and opposite to the torque 
caused toy the unbalanced condition. 

In this section we have discussed the prin- 
ciples of operation of the Mk 23 gyrocompass. 
In principle, to this point, our Mk 23 gyrocompass 
accurately indicates north, has a followup system 
to keep the phantom aligned with the gyrosphere, 
can transmit heading data to remote indicators, 
is supported in a manner that is adequate for 
installation atooard ship, and has toeen corrected 
for any factors that might cause errors in the 
heading data it provides. 

In the next section of this chapter you will 
find toasic information on the equipment which 
comprises the Mk 23 gyrocompass. 

MK 23 GYROCOMPASS 
EQUIPMENT 

The original Mk 23 gyrocompass (Mod 0) 
has toeen modified several times since it was 
introduced for service in the 1950's. Most of 
the modifications have been minor in nature. 
The modification that resulted in the greatest 
change to the Mk 23 Mod was the Mk 23 Mod 
C-3. We will discuss the equipment for tooth 
these systems so that you may compare the 
differences. 

The Mk 23 Mod and Mk 23 Mod C-3 gyro- 
compasses are compensated for speed error, 
V.E.R. error, and unbalance about the horizontal 
axis. The compasses are capable of indicating 
true north accurately in latitudes up to 75N 



or S, or they may be used as a directional gyro 
when nearer the poles. An electronic followup 
system is provided which furnishes accurate 
transmission of heading data to remote indi- 
cators (repeaters). 

The equipment which comprises the Mk 23 
Mod and the Mk 23 Mod C-3, figures 12-18 
and 12-19, consists of the master unit, control 
cabinet, speed unit, alarm control unit, and 
visual alarm unit. The Mk 23 Mod C-3 has 
two additional units: the power supply unit and 
the power supply control unit. The control 
cabinets, their circuitry and, of course, the 
two power supply units comprise the major 
differences in the Mk 23 Mod and Mk 23 
Mod C-3. The other equipment, which make 
up the two gyrocompasses, is very similar 
with only minor differences. 

Master Unit 

The master units of the Mk 23 Mod and 
.Mod C-3 are very similar and consist (fig. 
12-20) of a shock-mounted, oil-filled binnacle 
and the gyrocompass element. The unit is de- 
signed for deck mounting and weighs approx- 
imately 100 pounds. 

The gyrocompass element (fig. 12-21) is 
the principal unit of the compass system and 
consists of the sensitive element, phantom ele- 
ment, and spider element. The sensitive element 
consists of the vertical ring and gyrosphere. 
The sensitive element is the north- seeking part 
of the compass. 

The phantom element is supported on ball 
bearings, located within the spider, and rotates 
about the vertical axis of the gyrosphere. The 
phantom element is maintained in alignment 
with the sensitive element by the followup system. 

The spider element supports the phantom, 
gyrosphere, and vertical ring assembly. The 
spider, in turn, is supported by the gimbal rings; 
the complete gyrocompass element is supported 
within the binnacle. 

Control Cabinet 

The control cabinets for the Mk 23 Mod 
(fig. 12-18) and Mk 23 Mod C-3 (fig. 12-19) 
gyrocompasses contain the control devices, fol- 
lowup amplifier, azimuth control amplifier, 
leveling control amplifier, and other components 
necessary fortheproper operation of the compass, 
Both control cabinets are very similar in oper- 
ation. Their principal difference is that vacuum 
tubes are used in the Mod control cabinet, 



270 



Chapter 12 GYROCOMPASSES 




ALARM CONTROL UNIT 





SPEED UNIT 



VISUAL ALARM 
INDICATOR 




CONTROL CABINET 




MASTER UNIT 



Figure 12-18. Mk 23 Mod gyrocompass equipment. 

271 



7.167 



SHIPBOARD ELECTRICAL SYSTEMS 






POWER SUPPLY 
CONTROL UNIT 



VISUAL ALARM 
INDICATOR 




ALARM 

'CONTROL UNIT 



Figure 12-19. Mk 23 Mod C-3 gyrocompass equipment. 

272 



SPEED 
UNIT 



7.167X 



Chapter 12 GYROCOMPASSES 



BINNACLE 




GYROCOMPASS 
ELEMENT 



Figure 12-20. Mk 23 Mod C-3 master unit. 
273 



7.169X 



SHIPBOARD ELECTRICAL SYSTEMS 



ELECTROLYTIC 

LEVEL- 



VERTICAL 

RING 



GYROSPHERE 



LEVELING 
TORQUER 




GiiViBAL 
RING 



SPEED 

RESOLVER 



HEADING SYNCHRO 
TRANSMITTER 



SPJDtR 



Figure 12-21. Gyrocompass element. 



27.160 



while solid state devices are used in the Mod 
C-3 control cabinet. 

Circuits within both control cabinets make 
it possible for the operator to start and settle 
the gyrocompass on the meridian within 30 
minutes vice the 4-hour settling time normally 
required. Other circuits permit the gyrocompass 
to be used as a directional gyro near the poles. 
In this mode of operation the gyro is aligned 
with an imaginary point (not the north pole) 



which is then used as the reference point for 
navigation in lieu of the north pole. 

Instructions for starting and stopping the 
gyrocompass are located on the front of the 
control cabinet; more detailed instructions are 
contained in the manufacturer's technical manual. 

Speed Unit 

The speed unit, figures 12-18 and 12-19, 
contains the necessary components to produce 



274 



Chapter 12 GYROCOMPASSES 



an electrical signal proportional to the ship's 
speed. Speed data are received from the ship's 
underwater log or can be set in manually. The 
speed range of the unit is to 40 knots. 

Alarm Control Unit 

The alarm control, figures 12-18 and 12-19, 
contains the necessary relays and components 
to actuate a Hashing light or alarm tell when 
certain portions of the system become inoperative. 

Visual Alarm Indicator 

The visual alarm indicator, figures 12-18 
and 12-19, provides an indication of problems 
within the gyrocompass system. Under normal 
conditions the lamp on the indicator is lighted 
continuously. Flashing of the lamp, or if the 
lamp is out, indicates a failure within the gyro- 
compass system. 

Alarm Bell and 
Annunciator 

In some installations an alarm bell or elec- 
tronic signal unit (chapter 8) is used instead 
of, or in conjunction with, the visual alarm 
indicator. 

Power Supply Control 
Unit and Power Supply Unit 

The power supply control unit and the power 
supply unit (fig. 12-19) together with a 120- VDC 
battery form a standby supply which provides 
the Mk 23 Mod C-3 gyro with an uninterrupted 
supply of 120-V, 400-Hz, 3-phase power. If the 
normal ship's supply fails, the two units, using 
the battery as a power supply, produce the 
400-Hz power required to keep the compass 
operational for a limited period. 

Mk 19 MOD 3 
GYROCOMPASS 

The Mk 19 Mod 3 gyrocompass is an elec- 
tronic gyrocompass that furnishes heading data 
that is considered accurate enough (0.3) for 
navigational and fire control purposes. In addi- 
tion to own ship's heading data, it accurately 
measures and transmits the roll and pitch angles 
of the vessel on which it is installed. This roll 
and "pitch angle information is used to stabilize 
gunmounts, missile launchers, and other equip- 
ment which must remain level with the earth's 
surface to operate properly. 



The Mk 19 Mod 3 gyrocompass is capable 
of operating accurately in latitudes up to 75N 
or S. The Mk 19 Mod 3B, 3C, 3D, 3E f and some 
versions of the Mod 3A are capafcle of operating 
at higher latitudes or as directional gyros. 

The Mk 19 gyrocompass is designed on the 
principle that two properly controlled hori- 
zontal gyros together can furnish a stable 
reference for the measurement of ship's head- 
ing, roll and pitch. The spin axes of the two 
gyros are maintained horizontal and in the 
north-south and east- west planes toy the appli- 
cation of torques about the axis of tooth gyros. 

Briefly, the compass (fig. 12-22) consists 
of two gyros placed with their spin axes dis- 
placed 90 from each other in a horizontal 



ELECTROLYTIC 
BUBBLE LEVEL 



VERTICAL RING 



CRADLE 



AZIMUTH 
TORQUER 



SLAVING 
TORQUER 



SLAVING 
PICKOFF 



MERIDIAN 
GYRO 



AZIMUTH 

FOLLOW-UP 

PICKOFF 



LEVELING 
TORQUER 



ROLL-PITCH 
PICKOFF 




AZIMUTH 

FOLLOW-UP 

MOTOR 



ELECTROLYTIC 
BUBBLE LEVEL 



LEVELING 
TORQUER 



SLAVE 
GYRO 



27.168 

Figure 12-22. Simplified diagram of the Mk 19 
Mod 3 gyrocompass element. 



275 



SHIPBOARD ELECTRICAL SYSTEMS 



plane. The spin axis of one gyro is made to 
align itself north-south (meridian gyro); the 
spin axis of the other gyro is slaved (slave 
gyro) to the north indicating gyro so that it 
points in a direction 90 away from the first 
gyro (east-west). The meridian gyro and the 
slave gyro are mounted one above the other in 
a supporting ring. The ring is made to follow 
the gyros in heading and tilt by azinrath, roll, 
and pitch servos. These servos also drive the 
synchro transmitters which serve to supply 
roll, pitch, and azimuth (O.S.H.) synchro data. 

The meridian gyro is essentially a conven- 
tional gyrocompass, which furnishes indications 
of azimath as well as tilt about its horizontal 
axis. The slave gyro is essentially a directional 
gyro, which furnishes an indication of only tilt 
about its horizontal axis. 

The compass is compensated for speed, ac- 
celeration, earth rate, and shift in balance. 

An electronic control system is used in the 
Mk 19 Mod 3 gyrocompass to make it seek and 
indicate true north as well as the zenith. The 
electronic control system employed on the Mk 
19 Mod 3, 3A, and 3B is very similar to that we 
described earlier for the Mk 23 gyrocompass. 
Later modifications of the Mk 19 (Mod 3C, 3D, 
etc.) employ an accelerometer instead of the 
electrolytic level as the gravity sensitive device 
in their gravity reference systems. Both the 
electrolytic level and the accelerometer measure 
the angle of the gyro's spin axis with respect 
to the earth's surface and provide an electrical 
signal when the axis is not level. This signal, 
after amplification, is used to apply torques 
electrically to settle the gyro on the meridian 
and level. 

Both the meridian gyro and the slave gyro 
are enclosed in hermetically sealed spheres 
which are suspended in oil. The weight and 
buoyancy of the spheres are adjusted until they 
are weightless in oil. 

The system consists of four major components: 
the master compass, control cabinet, compass 
failure annunciator, and standby supply. The Mk 
19 Mod 3 and 3A employ a motor-generator 
type standby power supply, as shown in figure 
12-23. The Mk 19 Mod 3B and later modifications 
employs a static-type standby power supply. 



MASTER COMPASS 

The master compass (fig. 12-24) consists 
of two major elements; the compass element 
and the supporting element. 



Compass Element 

The compass element includes the sensitive 
element (meridian gyro and slave gyro) and the 
phantom assembly. The phantom assembly in- 
cludes: the azimuth phantom, which is main- 
tained in north- south alighment with the meridian 
gyro by means of the azimuth followup system; 
and the roll-pitch, phantom, which is maintained 
level with the earth's surface by means of elec- 
trical signals from both gyros and the roll- 
pitch followup system. 

Supporting Element 

The supporting element includes the gimbals, 
the frame, and the binnacle. The gimbals permit 
the ship to roll about the sensitive element 
60 and to pitch about the sensitive element 
40. 

CONTROL CABINET 

The control cabinet (fig. 12-23) contains 
the controlling devices, d.c. power supplies, 
analog computers, amplifiers, alarm system, 
and other assemblies required for operating 
and indicating the condition of the gyrocompass 
system. Some of the devices contained within 
the control cabinet include: the roll, pitch and 
azimath followup amplifiers; the analog com- 
puter, which provides electrical signals that 
correct for those factors which could produce 
errors in the compass; and the starting control 
systems. 

Starting Control Systems 

To aid in starting and operating the master 
compass, two starting systems are provided 
the fast-erect system and the fast- settling system. 

The fast-erect system is provided to level 
both gyros when starting the compass. 

The fast-settling system Is employed to reduce 
the time required for the gyros to assume a 
true level position and for the meridian gyro to 
settle on the true meridian. 

COMPASS FAILURE 

ANNUNCIATOR 

The compass failure annunciator (fig. 12-23) 
is a remote visual indicator, similar to the one 
described for the Mk 23 gyrocompass. Not all 
installations aboard ship include the compass 
failure annunciator. The alarm systems for Mk 



276 



Chapter 12 GYROCOMPASSES 



MASTER 
COMPASS 




CONTROL 
CABNET 





COMPASS FAILURE 
ANNUNCIATION 



STANDBY POWER SUPPLY 




27.169: 



Figure 12-23. Mk 19 Mod 3 gyrocompass equipment. 

277 



SHIPBOARD ELECTRICAL SYSTEMS 



GIMBAL RING 



PITCH DATA 



MERIDAN 
GYRO 



PHANTOM 
ASSEMBLY 



SLAVE 
GYRO 




STARBOARD VIEW 



PORT VIEW 



27JL70X 

Figure 12- 24. Two views of master compass (with covers removed) showing compass element and 

supporting element. 



19 gyrocompass installations vary with each 
ship. Some type of audible alarm device is 
usually used in conjunction with the compass 
failure annunciator when it is installed* 

STANDBY POWER 
SUPPLIES 

The standby power supply (fig. 12-23) is a 
motor-generator set which provides emergency 
power to the Mk 19 Mod 3 and 3A compass 
systems, in case the normal ship's supply fails. 

Under normal operation the standby power 
supply consists of a 11 5- volt, 400 -Hz, 3-phase 
synchronous motor (a.c. section), driving a 120- 
volt, compound-wound d.c. generator, which 
charges a bank of twenty 6- volt storage batteries. 
If the ship's 400-Hz supply fails, or falls below 
102 volts, the ship's line is disconnected auto- 
matically and the 120-volt d.c. generator operates 
as a motor powered by the storage batteries. 
The a.c. section now operates as a 115-volt, 
400-Hz, 3-phase generator supplying the compass 



system. The standby power supply for the Sperry 
Mk 19 Mod 3B gyrocompass is a static unit 
with no moving parts other than relays. The 
standby power supply of the Mk 19 Mod 3C 
and above is a modified version of the Mk 19 
Mod 3B standby power supply. The modified 
standby power supplies for these later modi- 
fications of the Mk 19 are referred to as static 
power supplies, and they are used as the primary 
power supply for the compass vice the ship's 
400-Hz supply. 



GYROCOMPASS RECORDS 
AND LOGS 

The Gyro Service Record Book is provided 
with each gyrocompass. The book stays with its 
gyrocompass and is a record of the compass 
from its construction through its entire life 
cycle. The book contains acceptance, test, and 
installation data as well as information per- 
taining to the overhaul, repair, and inspections 



278 



Chapter 12 GYROCOMPASSES 



of the gyrocompass. In the event a compass is 
to be removed from a ship, the appropriate 
entries are made in its Gyro Service Record 
Book, and the Tbook is transferred with the 
gyrocompass. 

Maintaining the Gyro Service Record Book 
is required by NAVSEA Systems Command. 
Instructions, procedures in case of its loss, 
etc. are found in the front of the Gyro Service 
Record Book and in Naval Ship's Technical 
Manual chapter 252 (9240.) Two pages are shown 
in figure 12-25. The page entitled ' 'Inspection, 
Overhaul, and Repair" is completed and signed 
by the gyro electrician who completes the repair. 
In the event unfavorable conditions are found 
during an inspection by an off -ship facility, 
a report must be made to the commanding 
officer. Planned maintenance completed by ship's 
force personnel is recorded by normal PMS 
reporting procedures and is not recorded in 
this book. However, a fault found during PMS, 
and then repaired, will be entered in the Gyro 
Service Record Book, as well as reported through 
MDCS. 

U.S. Navy Regulations and OPNAVINST 3120.32 
assign responsibility for the care and main- 
tenance of the gyrocompass equipment to the 
engineering officer and the electrical officer. 
The Gyrocompass Service Record Book contains 
items that are to be completed by the navigator. 
However, these are normally delegated and com- 
pleted by either the engineering officer or the 
electrical officer who may also be designated as 
the gyro officer. 

Some ships and type commands require that 
additional, locally prepared logs, records, etc. 
be maintained. If required, these records should 
be maintained completely and accurately and 
checked routinely by supervisory personnel, A 
major problem with all records is that, when 
neglected or when entries are omitted for any 
reason, they give a false record of reliability. 
Therefore, all records including MDCS docu- 
mentation must be checked to ensure that they 
are dated, complete, and accurate. 

Although not maintained by the electrical 
division personnel, the Magnetic Compass Record 
Book can be used to get data on the accuracy of 
the ship's gyrocompass system. This is a legal 
record required by Navy Regulations and OP- 
NAVINST 3120.32 and is maintained by the quar- 
termasters under the supervision of the navigator. 
It contains a record of the errors of the gyro- 
compass, the steering repeater, and the magnetic 
compass; entries are made every half-hour 
while the ship is underway. 



GYROCOMPASS MAINTENANCE 
AND REPAIR 

The gyrocompasses presently in use will 
give little trouble if they are properly main- 
tained and if operator/repair personnel are 
properly trained, motivated, and supervised. 

All persons associated with the gyrocompass 
installation should complete the applicable por- 
tions of the Personnel Qualifications Standards 
for that particular type of gyrocompass system, 
If correctly used, the PQS will ensure that per- 
sonnel assigned to the operation, maintenance, 
and watchstanding duties have the knowledge 
necessary to adequately perform these duties. 
Supervision will ensure that personnel are 
carrying out these duties in the prescribed 
manner. 

Corrective maintenance must be performed 
by knowledgeable personnel who follow the manu- 
facturer's manual. Formal training on a par- 
ticular gyrocompass system, although desirable, 
is not a necessity. The gyro electrician should, 
however, be thoroughly familiar with the manu- 
facturer's manual and the installed system,, The 
manufacturer's manual is the ultimate aid in 
all phases of training and repair. It contains 
sections devoted to the localization and isolation 
of malfunctions; therefore, all work must be 
conducted by persons familiar with these pro- 
cedures. The manufacturer's manual not only 
indicates procedures that should be followed, 
but also warns of what cannot be done without 
causing further damage to the system. An im- 
properly trained or careless repairman who is 
unfamiliar with, or is not following, the manu- 
facturer's manual can easily cause additional 
problems. For example, the movement of a 
weight on a mechanical gyro or the turning of the 
wrong potentiometer in an electronic gyrocompass 
system can change a period or dampening setting 
which will require recalibration of the gyro- 
compass system at a shore-based repair facility. 

All corrective maintenance and inspections 
conducted by outside activities must be recorded 
in the Gyro Service Record Book and through 
MDCS documentation to provide accurate indi- 
cations of reliability, cost, and repair man- 
hours. The PQS, PMS, and MDCS programs 
standardize training, documentation, and pre- 
ventive and corrective maintenance. These pro- 
grams, if properly implemented and supervised, 
will ensure . the most effective and reliable 
operation of the gyrocompass system*. If these 
programs are administered in a haphazard man- 
ner, equipment operation will deteriorate. 



279 



SHIPBOARD ELECTRICAL SYSTEMS 























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280 



Chapter 12 GYROCOMPASSES 



GYROCOMPASS OPERATION 

Because of its importance to the ship's 
safety during underway periods and in the oper- 
ation and maintenance of weapons systems, stand- 
ard gyrocompass operating procedures should 
be prescribed. 

When the gyrocompass is started for any 
reason, an entry should be made in the Engineer- 
ing Log. When the gyrocompass is started prior 
to getting underway, the station keeping the 
Preparation for Getting Underway Check-Off 
List (usually the quarterdeck) must also be 
notified. Prior to getting underway, usually when 
the Special Sea and Anchor Detail is set, entries 
should be made in both the Engineering Log and 
the Quartermaster's Notebook, indicating which 
gyrocompass (if more than one is installed) is 
the master (on line). While underway, the master 
will be changed only in the event of a casualty 
or with prior approval. The OOD must be kept 



fully informed of all of these changes. In the 
event of a casualty, the bridge must be noti- 
fied immediately, and the engineering officer 
of the watch should be notified as soon as 
possible; both will be informed of the nature 
of the casualty which necessitated the change. 

When the ship enters port, the gyrocompass 
systems should be secured only after permission 
has been obtained from the navigator and the 
commanding officer, via the engineering officer. 
Although not required for ship's safety, it may 
be advantageous to find out what requirements 
other departments have for the inport period, 
as many of their preventive maintenance pro- 
cedures require gyro inputs. Mutual coordination 
and cooperation with other divisions which may 
require gyrocompass inputs while in port, will 
aid in the most efficient use of the system and 
also will keep operating hours at a minimum 
while still providing required services. 



281 



INDEX 



60-hertz alternators, 14-15 

400-HZ generator, 15-16 

30 kW motor generator set, 16 

5 kW 250 VDC, 120 VAC 400 Hz static 
inverter, 24-26 

30 kW motor generator set, 16 

150 kW 440 VAC 60-Hz, 450 VAC 400-Hz 
static converter, 26-30 

AC controllers, 64-66 

low- voltage release (LVR), 66 
low- voltage protection (LVP) f 66 
low- voltage release effect (LVRE) , 66 

AC motors, 55-62 

capacitor motor, 60-61 
polyphase induction motors, 56-58 
single-phase motors, 58-59 
split-phase motor, 59-60 
universal motor, 61-62 

Alarm annunciators, 149-152 
IC/M alarm module, 151-152 
two-line alarm unit, 150-151 

Alarm and warning systems, 137-158 

alarm panels and switchboards, 152-155 

alarm panels, 152 

alarm switchboards, 152-155 
alarm systems, 155-157 

circulating-water, high-temperature 
alarm system, 157 

combustion gas and smoke detector 
system, 157 

generator air high-temperature alarm 
and the generator bearing high- 
temperature alarm systems, 157 

high-temperature alarm systems, 
156-157 

lubricating-oil, low-pressure alarm 
system, 157 

sprinkling alarm system, 157 



Alarm and warning systems continued 
audible signals, 146-148 

bells and buzzers, 146-147 

electronic signal units, 148 

horns and sirens, 147-148 
switches, 137-146 

combustion gas and smoke detector, 
145-146 

lever-operated switch, 137-141 

liquid-level float switch, 145 

mechanical switch, 145 

pressure switch, 141-142 

thermostatic switches, 142-144 
systems maintenance, 157-158 
visual signals, 148-152 

alarm annunciators, 149-152 

lamp-type indicators, 148-149 

Alarm switchboards, 152-155 

two-line unit alarm switchboard, 152 
type IC/SM alarm switchboard, 152-155 

Alarm systems, 155-157 

circulating- water, high- temperature 
alarm system, 157 

combustion gas and smoke detector 
system, 157 

generator air high-temperature alarm 
and the generator bearing high- 
temperature alarm systems, 157 

high-temperature alarm system, 156-157 

lubricating-oil, low-pressure alarm 
system, 157 

sprinkling alarm system, 157 

Alarm panels and switchboards, 152-155 
alarm panels, 152 
alarm switchboards, 152-155 

type IC/SM alarm switchboard, 152-155 
two-line unit alarm switchboard, 152 
Alarm panels, 152 

Alternating current generators, 13-14 
construction of alternators, 13-14 
types of drive, 14 



282 



INDEX 



Amplified voice systems, 227-254 
announcing and intercommunicating 
systems, 227-235 
central amplifier announcing systems, 

227-235 

intercommunicating systems, 235 
interior voice communications system, 
247-254 
IVCS, 248-250 
IVCS organization, 250-254 
IVCS summary, 254 
ship's entertainment systems, 235-238 

ship's entertainment equipment, 235-238 
ship's entertainment system operation, 

238 

sound motion picture systems, 238-247 
sound motion picture film, 238-242 
sound motion picture projection 
equipment, 242-247 

Announcing and intercommunicating systems, 
227-235 

central amplifier announcing systems, 
227-235 

1MC-6MC announcing systems equipment, 

227-234 
1MC-6MC announcing systems operation, 

234-235 

maintenance and safety, 235 
intercommunicating systems, 235 
intercom unit, 235 

Annunciators, 204-205 

Arma dead reckoning equipment, 184-187 
arma dead reckoning analyzer, 184 
arma dead reckoning tracer, 184-186 
dead reckoning indicator, 186-187 

Audible signals, 146-148 

bells and buzzers, 146-147 
electronic signal units, 148 
horns and sirens, 147-148 

Automatic degaussing systems, 102-117 
GM-1A automatic degaussing system, 

114-117 

SM-9A automatic degaussing system, 
117 

degaussing switchboard, 117 
SSM automatic degaussing system, 106-114 
automatic channels (A & FI-QI), 

109-112 

coil power supplies, 112-114 
degaussing switchboard, 106-109 
manual channels (M & FP-QP), 109 



Auxiliary shipboard equipment, 118-136 
batteries, 118-126 

battery maintenance, 124-126 

primary cell, 118 

secondary cell, 118 

types of batteries, 118-124 
battery charging equipment, 126-127 
electric galley equipment, 128-129 

deep fat fryers, 129 

electric galley equipment maintenance, 
129 

ovens, 128-129 

ranges, 128 

electrical forklift trucks, 127-128 
fin stabilizer systems, 131-132 

fin stabilizing system maintenance, 132 

general description, 132 

principles of operation, 132 
laundry equipment, 129-131 

laundry equipment safety and 
maintenance, 130-131 

washer-extractor, 129-130 
small boat electrical systems, 127 
steering systems, 132-136 

remote steering control system, 136 

steering gear, 133-136 



Basic operation of shipboard degaussing, 
97-99 

degaussing coils, 97-99 
A coil, 99 

F and Q coils, 98-99 
L coil, 99 
M coil, 98 
Batteries, 118-126 

battery maintenance, 124-126 
dry cell maintenance, 124 
dry cell safety precautions, 125 
lead-acid battery maintenance, 124-125 
lead-acid battery safety precautions, 

125-126 

nickel-cadmium battery care, 125 
nickel-cadmium battery safety 
precautions, 126 
primary cell, 118 
secondary cell, 118 
types of batteries, 118-124 
dry cell, 118-120 
secondary (wet) cells, 120-124 
Batteries, types of, 118-124 
dry cell, 118-120 
secondary (wet) cells, 120-124 



283 



SHIPBOAKD ELECTRICAL SYSTEMS 



Battery charging equipment, 126-127 

Battery maintenance, 124-126 
dry cell maintenance, 124 
dry cell safety precautions, 125 
lead-acid toattery maintenance, 124-125 
lead-acid toattery safety precautions, 

125-126 

nickel-cadmium toattery care, 125 
nickel-cadmium toattery safety 
precautions, 126 

Bells and buzzers, 146-147 

Blue illumination, 76-77 

Bus toars, 40 

Bus transfer equipment, 44-45 



Connecting and disconnecting shore 
power, 5-7 

Construction of alternators, 13-14 
Control cabinet, 276 

starting control systems, 276 
Control devices, 42 
Controllers, 62-68 

AC controllers, 64-66 

low-voltage protection (LVP), 66 

low-volage release (LVR), 66 

low-voltage release effect (LVRE), 66 

DC controllers, 62-64 

logic controllers, 66-68 



D 



Calibration ranging, 97 
Call-toell systems, 203-205 

annunciators, 204-205 

circuit A, 204 

circuit E, 203-204 
Calls, types of, 225 
Capacitor motor, 60-61 
Casualty power distritoution system, 33-36 
Cell valve, 162 

Central amplifier announcing systems, 
227-235 

1MC-6MC announcing systems 
equipment, 227-234 

1MC-6MC announcing systems operation, 
234-235 

mainenance and safety, 235 
Changing coil currents, 102 
Characteristics, 70 
Check ranging, 97 
Circuit A, 204 
Circuit toreakers, 37-40 

selective tripping, 38-40 
Circuit E, 203-204 
Circulating-water, high-temperature 

alarm system, 157 
Classification of circuits, 52 
Comtoined static exciter and voltage 
regulation system, 17-22 

automatic voltage regulation, 18-22 

field flashing circuit, 18 

manual voltage control, 22 
Combustion gas and smoke detector, 

145-146 

Combustion gas and smoke detector 
system, 157 

Compass failure annunciator, 276-278 
Compound motors, 55 



Darkened ship equipment, 75-76 
DC controllers, 62-64 

DC motors, 53-55 

compound motors, 55 
series motors, 54-55 
shunt motors, 53-54 
stabilized shunt motors, 55 
Dead reckoning systems, 183-192 
arma dead reckoning equipment, 
184-187 

arma dead reckoning analyzer, 184 
arma dead reckoning tracer, 184-186 
dead reckoning indicator, 186-187 
NC-2 plotting systems, 188-192 
NC-2 Mod 0, 188-189 
NC-2 Mod 1/1A, 189-191 
NC-2 Mod 2/2A, 191-192 
PT-512/S tactical display plotting 
table (formerly NC-2 Mod 3), 192 
new design dead reckoning equipment, 
187-188 

dead reckoning tracer Mk 6 Mod 4B, 

188 

Mk 9 Mod 4 DRAI, 187-188 
Deep fat fryers, 129 
Degaussing, 93-117 

automatic degaussing systems, 102-117 
GM-lA automatic degaussing system, 

114-117 
SM-9A automatic degaussing system, 

117 
SSM automatic degaussing system, 

106-114 

basic operation of shipboard degaussing, 
97-99 

degaussing coils, 97-99 
earth's magnetic field, 93-94 



284 



INDEX 



Degaussing continued 

magnetic ranges and ranging, 97 
calibration ranging, 97 
check ranging, 97 
degaussing folder, 97 
manual degaussing systems, 99-102 
changing coil currents, 102 
motor-generator control, 100-101 
polarity, 101-102 
rheostat control, 99-100 
ship's magnetic field, 94-97 

ship's induced magnetization, 95-97 
ship's permanent magnetization, 

94-95 

Degaussing coils, 97-99 
A coil, 99 

F and Q coils, 98-99 
L coil, 99 
M coil, 98 

Degaussing folder, 97 
Designation, 69-70 

Dial telephone switchboard equipment, 207-217 
automatic electric switchlboard equipment, 
209-217 

Dial telephone system maintenance, 225-226 
Dial telephone systems, 205-226 

dial telephone switchboard equipment, 
207-217 

automatic electric switchboard 

equipment, 209-217 

dial telephone system maintenance, 225-226 
marine dialmaster dial telephone 
switchboard equipment, 217-225 
attendant's cabinet, 224-225 
MDM/100-15 switchboard, 218-223 
power and signaling equipment, 224 
system operation, 223-224 
safety, 225 
telephone station equipment, 206-207 

types of telephones, 206-207 
types f calls, 225 

Direct current generators, 12-13 
Disconnect links, 40-41 
Distribution systems, 31-52 

emergency power distribution, 31-36 
casualty power distribution system, 

33-36 

interior communications distribution, 45-52 
classification of circuits, 52 
1C switchboard, 46-48 
1C switchboard power supply, 48-52 
local 1C switchboards, 52 
load centers and power panels, 45 
ship's service power distribution, 31 



Distribution systems continued 
switchboards, 36-45 
bus bars, 40 

bus transfer equipment, 44-45 
circuit breakers, 37-40 
control devices, 42 
disconnect links, 40-41 
monitoring devices, 41-42 
protective devices, 42-43 
shore power connection, 43-44 

Drive, types of, 14 

Dummy log system, 182-183 



Earth's magnetic field, 93-94 
Earth's rotation, effect of, 259-261 
Electric galley equipment, 128-129 

deep fat fryers, 129 

electric galley equipment maintenance, 

ovens, 128-129 

ranges, 128 



129 



Electric galley equipment maintenance, 129 
Electrical forklift trucks, 127-128 
Electrical hazards, 1-2 
electrical shock, 1-2 

causes of electric shock, 2 

Electrical shock, 1-2 

causes of electric shock, 2 

Electrohydraulic load-sensing speed governor, 
22-23 

operation, 22-23 

Electronic signal unit, 148 
Emergency power distribution, 31-36 

casualty power distribution system, 33-36 



Fin stabilizer systems, 131-132 

fin stabilizing system maintenance, 132 

general description, 132 

principles of operation, 132 
Fin stabilizing system maintenance, 132 

Fluorescent lamps, 70-72 
characteristics, 70-72 
construction, 70 
operation, 70 



285 



SHIPBOARD ELECTRICAL SYSTEMS 



Generator air high-temperature alarm and 
the generator bearing high-temperature 
alarm systems, 157 
Glow lamps, 72 

GM-1A automatic degaussing system, 114-117 
Gyrocompass maintenance and repair, 279-281 
Gyrocompass operation, 281 
Gyrocompass records and logs, 278-279 

Gyrocompasses, 255-281 

gyrocompass maintenance and repair, 

279-281 

gyrocompass operation, 281 
gyrocompass records and logs, 278-279 
gyroscope, the, 255-261 

effect of earth's rotation, 259-261 

gyroscopic properties, 256-259 

three degrees of freedom, 256 
making the gyroscope into a gyrocompass, 
261-265 

seeking the meridian, 261-263 

settling on the meridian, 263-265 
Mk 19 Mod 3 gyrocompass, 275-278 

compass failure annunciator, 276-278 

control cabinet, 276 

master compass, 276 

standby power supplies, 278 
Mk 23 gyrocompass, 265-275 

Mk 23 gyrocompass equipment, 270-275 

Mk 23 gyrocompass principles of 
operation, 265-270 

Gyroscopic properties, 256-259 
forces of translation, 258-259 
precession, 257-258 
rigidity of plane, 256-257 

Gyroscope, the, 255-261 

effect of earth's rotation, 259-261 
gyroscopic properties, 256-259 

forces of translation, 258-259 

precession, 257-258 

rigidity of plane, 256-257 
three degrees of freedom, 256 



H 



Handsets, 193-194 

Headsets, 194-195 

High-temperature alarm system, 156-157 

Horns and sirens, 147-148 



1C switchboard, 46-48 
1C switchboard power supply, 48-52 
Incandescent lamps, 69 
Intercommunicating systems, 235 

intercom unit, 235 

Interior communication distribution, 45-52 
classification of circuits, 52 
1C switchboard, 46-48 
1C switchboard power supply, 48-52 
local 1C switchboards, 52 
Interior communications telephone systems, 
193-226 

call-bell systems, 203-205 
annunciators, 204-205 
circuit A, 204 
circuit E, 203-204 
dial telephone systems, 205-226 

dial telephone switchboard equipment, 

207-217 
dial telephone system maintenance, 

225-226 

marine dialmaster dial telephone 
switchboard equipment, 217-225 
safety, 225 

telephone station equipment, 206-207 
types of calls, 225 
sound-powered telephones, 193-203 
handsets, 193-194 
headsets, 194-195 
sound-powered telephone amplifier 

AM-2210/WTC, 202-203 
sound-powered telephone circuit 
maintenance, 202 

sound-powered telephone systems and 
circuits, 195-202 

Interior voice communications system, 247-254 
IVCS, 248-250 

interior communications switching center 

(ICSC), 248-250 
terminal devices, 248 
IVCS organization, 250-254 
interfaces, 253 
special features, 253-254 
IVCS summary, 254 
IVCS, 248-250 

interior communications switching center 

(ICSC), 248-250 
terminal devices, 248 
IVCS organization, 250-254 
interfaces, 253 
special features, 253-254 
IVCS summary, 254 



286 



INDEX 



Lamp-type indicators, 148-149 
Laundry equipment, 129-131 

laundry equipment safety and maintenance, 

130-131 
washer-extractor, 129-130 

card-o-matic programmer, 130 
Laundry equipment safety and maintenance, 

130-131 

Lever-operated switch, 137-141 
Light sources, 69-72 
characteristics, 70 
designation, 69-70 
fluorescent lamps, 70-72 
characteristics, 70-72 
construction, 70 
operation, 70 
glow lamps, 72 
incandescent lamps, 69 
Lighting fixtures, 72-73 
Lighting systems, 74-77 
blue illumination, 76-77 
darkened ship equipment, 75-76 
red illumination, 76 

Line voltage regulator, type 1ES25007, 30 
Line voltage regulators, 30 

type 1ES25007 line voltage regulator, 30 
Liquid-level float switch, 145 
Load centers and power panels, 45 
Local 1C switchboards, 52 
Logic controllers, 66-68 
Lubricating-oil, low-pressure alarm 
system, 157 



M 



Maintenance, 92 

Maintenance and repair work, 7 

while working aloft, 7-8 
Magnetic ranges and ranging, 97 

calibration ranging, 97 

check ranging, 97 

degaussing folder, 97 
Magneto- voltmeter type, 169-170 
Making the gyroscope into a gyrocompass, 
261-265 

seeking the meridian, 261-263 

settling on the meridian, 263-265 
Manual degaussing systems, 99-102 

changing coil currents, 102 

motor-generator control, 100-101 

polarity, 101-102 

rheostat control, 99-100 



Marine dialmaster dial telephone switchboard 
equipment, 217-225 

attendant's cabinet, 224-225 
MDM/100-15 switchboard, 218-223 
power and signaling equipment, 224 
system operation, 223-224 
Master compass, 276 
compass element, 276 
supporting element, 276 
Mechanical switch, 145 
Mk 19 Mod 3 gyrocompass, 275-278 

compass failure annunciator, 276-278 
control cabinet, 276 

starting control systems, 276 
master compass, 276 
compass element, 276 
supporting element, 276 
standby power supplies, 278 

Mk 23 gyrocompass, 265-275 

Mk 23 gyrocompass equipment, 270-275 
alarm bell and annunciator, 275 
alarm control unit, 275 
control cabinet, 270-274 
master unit, 270 
power supply control unit and power 

supply unit, 275 
speed unit, 274-275 
visual alarm indicator, 275 
Mk 23 gyrocompass principles of operation, 
265-270 

followup system, 266-268 
gravity reference system, 265-266 
Mk 23 gyrocompass errors and 
correction, 268-270 

Mk 23 gyrocompass equipment, 270-275 
alarm bell and annunciator, 275 
alarm control unit, 275 
control cabinet, 270-274 
master unit, 270 
power supply control unit and power 

supply unit, 275 
speed unit, 274-275 
visual alarm indicator, 275 

Mk 23 gyrocompass principles of operation, 
263-270 

followup system, 266-268 
gravity reference system, 265-266 
Mk 23 gyrocompass errors and correction, 
268-270 

Monitoring devices, 41-42 

Motor-generator control, 100-101 

Motor generator mode 1, 23 

Motor generator mode 2, 23 



287 



SHIPBOARD ELECTRICAL SYSTEMS 



Motors and controllers, 53-68 
AC motors, 55-62 

capacitor motor, 60-61 

polyphase induction motors, 56-58 

single-phase motors, 58-59 

split-phase motors, 59-60 

universal motor, 61-62 
controllers, 62-68 

AC controllers, 64-66 

DC controllers, 62-64 

logic controllers, 66-68 
DC motors, 53-55 

compound motors, 55 

series motors, 54-55 

shunt motors, 53-54 

stabilized shunt motors, 55 



N 



Navigation and signal lights, 79-92 

floodlights and lanterns, 90-92 

navigation lights, 81-84 

signal lights (station or operational), 
84-86 

signal lights (visual communication), 

86-90 
NC-2 plotting systems, 188-192 

NC-2 Mod 0, 188-189 

NC-2 Mod 1/1A, 189-191 

NC-2 Mod 2/2A, 191-192 

PT-512/S tactical display plotting 
table (formerly NC-2 Mod 3), 192 
New design dead reckoning equipment, 187-188 

dead reckoning tracer Mk 6 Mod 4B , 
188 

Mk 9 Mod 4 DRAI, 187-188 
No-break power supply system, 23 

motor generator mode 1, 23 

motor-generator mode 2, 23 
Nonstandard alterations and equipment, 8 



Ovens, 128-129 



Polarity, 101-102 

Polyphase induction motors, 56-58 

Portable electrical equipment, 3-5 



Power supplies, 11-30 

60-hertz alternators, 14-15 
400-HZ generator, 15-16 

30- kW motor generator set, 16 
alternating current generators, 13-14 
construction of alternators, 13-14 
types of drive, 14 
direct current generators, 12-13 
line voltage regulators, 30 

type 1ES25007 line voltage regulator, 

30 

no-break power supply system, 23 
motor generator mode 1, 23 
motor-generator mode 2, 23 
speed regulation, 22-23 

electrohydraulic load-sensing speed 

governor, 22-23 
static power supplies, 23-30 

5 kW 250 VDC, 120 VAC 400 Hz static 
Inverter, 24-26 

150 kW 440 VAC 60-Hz, 450 VAC 
400-Hz static converter, 26-30 
voltago produce*! by magnetism, 11-12 
voltage regulators, 16-22 

combined static exciter and voltage 
regulation system, 17-22 

Pressure switch, 141-142 

Primary cell, 118 

Propeller revolution indicator system, 
167-170 

magneto-voltmeter type, 169-170 
synchro-type equipment, 168-169 

Protection devices, 42-43 



Ranges, 128 

Red illumination 9 76 

Remote steering control system, 136 

Repienishment-at-sea red lighting, 77-78 
hull contour lights, 77-78 
lights for work areas, 78 
obstruction lights, 78 
phone/distance line marking, 78 
station marker light box, 78 

Rheostat control, 99-100 

Rudder angle indicator system, 167 

Rudder order system, 166-167 

Rudder order and rudder angle indicator 
systems, 164-167 

rudder angle indicator system, 167 
rudder order system, 166-167 



288 



INDEX 



Safety, 1-10, 160, 164, 175, 225 
electrical hazards, 1-2 

electrical shock, 1-2 
safety inspections, 8-10 
safety requirements, 2-8 

connecting and disconnecting shore 
power, 5-7 

in maintenance and repair work, 7 
in portable electrical equipment, 3-5 
in using cleaning solvents, 6-7 
in work areas, 2-3 
nonstandard alterations and 

equipment, 8 

safety training program, 2 
Safety inspections, 8-10 
Safety requirements, 2-8 

connecting and disconnecting shore 
power, 5-7 

in portable electrical equipment, 3-5 
in maintenance and repair work, 7 
in using cleaning solvents, 6-7 

precautions with cleaning solvents, 

6-7 

in work areas, 2-3 

nonstandard alterations and equipment, 8 
Safety requirements in work areas, 2-3 
Safety training program, 2 
Salinity cell, 161-162 
Salinity indicator panel, 162-164 

IC/D5RM salinity indicator panel, 163-164 
IC/E1U-S3 salinity indicator panel, 

162-163 

Salinity indicator system, 160-164 
cell valve, 162 
safety, 164 
salinity cell, 161-162 
salinity indicator panel, 162-164 
IC/D5RM salinity indicator panel, 

163-164 
IC/E1U-S3 salinity indicator panel, 

162-163 

Secondary cell, 118 
Seeking the meridian, 261-263 
Series motors, 54-55 
Settling on the meridian, 263-265 
Shipboard lighting, 69-92 
lighting fixtures, 72-73 
light sources, 69-72 
characteristics, 70 
designation, 69-70 
fluorescent lamps, 70-72 
glow lamps, 72 
incandescent lamps, 69 



Shipboard lighting continued 
lighting systems, 74-77 
blue illumination, 76-77 
darkened ship equipment, 75-76 
red illumination, 76 
maintenance, 92 

special lighting applications, 77-92 
navigation and signal lights, 79-92 
replenishment- at- sea red lighting, 

77-78 

visual landing aids, 78-79 
transformers, 73-74 
Ship's entertainment equipment, 235-238 

commercial ship's entertainment equipment, 

236-238 

control/amplifier console, 236 
input equipment, 236 
loudspeakers, 236 

Ship's entertainment system operation, 

238 

Ship's entertainment systems, 235-238 
ship's entertainment equipment, 235-238 
commercial ship's entertainment 

equipment, 236-238 
control/ amplifier console, 236 
input equipment, 236 
loudspeakers, 236 
ship's entertainment system operation, 238 

Ship's indicating, order, and metering systems, 
159-192 

dead reckoning systems, 183-192 

arma dead reckoning equipment, 184-187 
new design dead reckoning equipment, 

187-188 

propeller revolution indicator system, 
167-170 

magneto-voltmeter type, 169-170 
synchro-type equipment, 168-169 
rudder order and rudder angle indicator 
systems, 164-167 

rudder angle indicator system., 167 
rudder order system, 166-167 
salinity indicator system, 160-164 
cell valve, 162 
safety, 164 
salinity cell, 161-162 
salinity indicator panel, 162-164 
tank level indicating systems, 159-160 

safety, 160 

underwater log and dummy log systems, 
175-183 

dummy log system, 182-183 
underwater log speed converter, 183 
underwater log system, 175-182 



SHIPBOARD ELECTRICAL SYSTEMS 



Ship's indicating, order, and metering 
systems continued 

wind direction and speed indicator system, 
170-175 
safety, 175 
wind direction and speed detector, 

170-173 
wind direction and speed transmitter, 

173-174 
wind speed and direction indicator, 

174-175 

Ship's induced magnetization, 95-97 
Ship's magnetic field, 94-97 

ship's induced magnetization, 95-97 
ship's permanent magnetization, 94-95 
Ship's permanent magnetization, 94-95 
Ship's service power distribution, 31 
Shore power connection, 43-44 
Shunt motors, 53-54 
Single-phase motors, 58-59 
SM-9A automatic degaussing system, 117 

degaussing switchboard, 117 
Small boat electrical systems, 127 
Sound motion picture film, 238-242 
film care, 238-239 
film construction, 238 
film management, 239-242 
Sound motion picture projection equipment, 
242-247 

movie projector operator training, 247 
projector maintenance, care, and safety, 

247 
sound motion picture film, 238-242 

Sound motion picture systems, 238-247 
sound motion picture film, 238-242 
film care, 238-239 
film construction, 238 
film management, 239-242 
sound motion picture projection 
equipment, 242-247 
movie projector operator training, 

247 

projector maintenance, care, and 
safety, 247 

Sound -powered telephone amplifier AM-2210/ 

WTC, 202-203 
Sound-powered telephone circuit maintenance, 

202 

Sound-powered telephone systems and 
circuits, 195-202 

plotters transfer switchboards, 201 
selector switches, 201-202 
string- type circuits, 201 
switchboard circuits, 200 
switchbox circuits . 200 - 20 1 



Sound-powered telephones, 193-203 
handsets, 193-194 
headsets, 194-195 
sound-powered telephone amplifier 

AM-2210/WTC, 202-203 
sound-powered telephone circuit 
maintenance, 202 

sound-powered telephone systems and 
circuit, 195-202 

plotters transfer switchboards, 201 
selector switches, 201-202 
string-type circuits, 201 
switchboard circuits, 200 
switchbox circuits, 200-201 

Special lighting applications, 77-92 
navigation and signal lights, 79-92 
floodlights and lantern, 90-92 
navigation lights, 81-84 
signal lights (station or operational) , 

84-86 
signal lights (visual communication) , 

86-90 

replenishment-at-sea red lighting, 77-78 
hull contour lights, 77-78 
lights for work areas, 78 
obstruction lights, 78 
phone/distance line marking, 78 
station marker light box, 78 
visual landing aids, 78-79 
Speed regulation, 22-23 

electrohydraulic load- sensing speed 
governor, 22-23 

operation, 22-23 
Split-phase motors, 59-60 
Sprinkling alarm system, 157 
SSM automatic degaussing system, 106-114 

automatic channels (A & FI-QI), 109-112 
coil power supplies, 112-114 
degaussing switchboard, 106-109 
manual channels (M & FP-QP), 109 
Stabilized shunt motors, 55 
Standby power supplies, 278 
Static power supplies, 23-30 

5 kW 250 VDC, 120 VAC 400 Hz 
static inverter, 24-26 
150 kW 440 VAC 60-Hz, 450 VAC 
400-Hz static converter, 26-30 
Steering gear, 133-136 
power unit, 133-136 
ram unit, 133 
Steering systems, 132-136 

remote steering control system, 136 
steering gear, 133-136 
power unit, 133-136 
ram unit, 133 



290 



INDEX 



Switchboards, 36-45 
bus bars, 40 

bus transfer equipment, 44-45 
circuit breakers, 37-40 

selective tripping, 38-40 
control devices, 42 
disconnect links, 40-41 
monitoring devices, 41-42 
protective devices, 42-43 
shore power connection, 43-44 

Switches, 137-146 

combustion gas and smoke detector, 

145-146 

lever-operated switch, 137-141 
liquid-level float switch, 145 
mechanical switch, 145 
pressure switch, 141-142 
thermostatic switches, 142-144 
mercury thermostatic switch, 

143-144 
thermostatic switch type IC/N, 

142-143 
water switch, 144-145 

Synchro-type equipment, 168-169 
Systems maintenance, 157-158 



Tank level indicating systems, 159-160 

safety, 160 
Telephone station equipment, 206-207 

types of telephones, 206-207 
Thermostatic switches, 142-144 

mercury thermostatic switch, 143-144 

thermostatic switch type IC/N, 142-143 
Three degrees of freedom, 256 
Transformers, 73-74 



U 



Underwater log and dummy log systems, 
175-183 

dummy log system, 182-183 
underwater log speed converter, 183 
underwater log system, 175-182 

electromagnetic principle, 175-176 
fixed rodmeter, 177-178 
indicator-transmitter, 178-182 
sea valve and rodmeter assemblies, 

176-177 
Underwater log speed converter, 183 



Underwater log system, 175-182 

electromagnetic principle, 175-176 

fixed rodmeter, 177-178 

indicator-transmitter, 178-182 

sea valve and rodmeter assemblies, 176-177 

Universal motor, 61-62 

Using cleaning solvents, 6-7 

precautions with cleaning solvents, 6-7 



Visual landing aids, 78-79 

Visual signals, 148-152 

alarm annunciators, 149-152 
IC/M alarm module, 151-152 
two-line alarm unit, 150-151 
lamp- type indicators, 148-149 

Voltage produced by magnetism, 11-12 

Voltage regulators, 16-22 

combined static exciter and voltage 
regulation system, 17-22 
automatic voltage regulation, 18-22 
field flashing circuit, 18 
manual voltage control, 22 



W 



Washer-extractor, 129-130 

card-o-matic programmer, 130 

Wind direction and speed detector, 170-173 

Wind direction and speed indicator system, 
170-175 
safety, 175 

wind direction and speed detector, 170-173 
wind direction and speed transmitter, 
173-174 

wind direction subassembly, 173-174 
wind speed subassembly, 174 
wind speed and direction indicator, 174-175 

Wind direction and speed transmitter, 173-174 
wind direction subassembly, 173-174 
wind speed subassembly, 174 

Wind speed and direction indicator, 174-175 



291 



9>U.S. GOVERNMENT PRINTING OTFICE: 1977-740-073/20